Smart NPC's

7 views
Skip to first unread message

root

unread,
Dec 29, 1995, 3:00:00 AM12/29/95
to

A while ago someone posted asking why we didn't have more 'believable'
NPCs. I made a bit of an explanatory post with regard to that, which
appears to have fallen into the bit bucket. Since I don't keep copies of
these things (normally), this is both rewrite and repost.

There will be a couple exercises for the reader, too. Grab a pencil and
a sheet of paper.

'Smart' NPC's in Interactive Fiction
(What we can and can't do, and why)

I can skip the obligatory definitions of IF, the player and so forth, so
let's go straight to the NPC. The NPC is some animate agent filling the
role of some other character in an IF story. (Black in Jigsaw; Edward
in Christminster; Floyd in Planetfall)

What do they do? (Not what function do they serve, that's for a
different newsgroup entirely)

An NPC responds to her surroundings in a consistant, and intelligent
way. That's the nub of it. Floyd (Planetfall) tried to make sensible
responses to player questions and speech, passed comment on anything
noteworthy that occurred and so forth.

However, IF NPC's are little more than random (or scheduled) machines
with stimulus-response mechanisms. (There is contention as to whether
humans are any more than this, but just several orders of magnitude more
complex, but that's a little out of our scope)

Now, we have NPC's that do this, but find them a little less than
satisfying. We want the 'Smart NPC'. This NPC does the same thing as the
one above, only more so, so let's break it down a little:

* Has goals.
* Seeks to accomplish those goals.
* Knows things.
* Remembers things.
* Can speak about what it knows or remembers.
* Can understand complex player input (like this sentence).

Let's look at a simple goal. Our NPC is in the attic, looking for an old
photograph. There's the usual paraphenalia of tea-chests, cardboard
boxes and locked trunks and suitcases.

Now, how does our NPC accomplish that goal? How would you do it, as an
IF player?

Exercise: Write down a set of actions, that you (the IF player) would
type to look for the photograph.
............
By now, we should have a lot of actions. How did you arrive at
these actions? You 'know' that objects can be inside certain other kinds
of objects (inside a box, or a barrel, but probably not inside a table)
or under or behind things. Currently, we have an action list that our
NPC can perform, to look for the photograph. What if the photograph
hasn't been found at the end of it? More actions in the list, then.

Can we specify more general rules so that we don't _need_ a large action
list? Let's write some simple rules:

Exercise: Attempt to write a set of simple rules to generate the same
kind of actions that are in the action list. An example:

If the object can contain things then
look inside it.

............
How did we do? Did you remember to look _under_ things? Behind them?
Now, we'll give these instructions to Virtual-Joe. Joe is our NPC.

Joe is here. Joe is looking for something.
> WAIT
Joe looks in the large tea-chest, and rummages for a minute. He shakes
his head and then looks around.
Joe is here. Joe is looking for something.
> WAIT
Joe looks under the sharp needle. "Where is that damn photograph," he mutters.

Oops. A needle is too small to conceal a photograph. But Joe doesn't
know that. We didn't tell him.

if the object is larger than the photograph then
look under it.

Hmm. We're missing something though. Cupboard, needle, and photograph
are just words. Joe doesn't know what is larger than what. So, we'll
have to make a list.

needle.size=1;
loose-marble.size=2;
photograph.size=3
teachest.size=12
trunk.size=15
box.size=9

Okay. Joe can now tell that he can't find the photograph under the
marble or the needle. This is good. We're not out of the woods, yet,
though...

Joe is here. Joe is looking for something.
> DROP BREADBOX
Joe looks under the breadbox, muttering.
Joe is here. Joe is looking for something.

See? We can keep lugging stuff up here, and Joe will dutifully look
under each thing that we drop that is large enough to conceal a photo.
Moreover he will also look inside it, if it's the sort of object that
can contain things.

Worse:
Joe is here. Joe is looking for something.
> GET STEAMER TRUNK
You heave the large steamer trunk up off the floor.
Joe looks in the large tea-chest, and rummages for a minute. He shakes
his head and then looks around.
Joe is here. Joe is looking for something.
> DROP IT
With a grunt, and a sigh of relief, you lower the trunk to the floor.
Joe looks under the large steamer trunk.

Joe has to be equipped with some kind of memory here. The photograph is
obviously not under the trunk (because we lifted it up). We need to tell
Joe not to try looking under it, in that case. What if we empty the box?
Will he still try to look inside it? Should he? How do we prevent this?

In the AI world, this field is called knowledge representation. We have
to find methods of representing these little bits of information so that
we can make them available to our behavioural 'rules' (which we did
earlier).

Now, presume that the steamer trunk is locked. How does Joe go about
solving this? Does he start looking for a key? Boltcutters? Hacksaw?
Or does he grab a Yellow Pages and call a locksmith? Does he just give
up?

The coder has to decide. In fact the coder has to be aware of everything
that can happen (at least in a general sort of way) or the game and
characters will not respond appropriately.

> GIVE PAPERWEIGHT TO JOE
Joe looks at the glass paperweight, turns it over and shrugs. "I
can't see this being a terrible lot of use just now." he says.
Nevertheless, he puts it in his pocket.

> GIVE BROKEN GLASS TO JOE
Joe looks at the collection of sharp shards, turns it over and shrugs. "I
can't see this being a terrible lot of use just now." he says.
Nevertheless, he puts it in his pocket.

(Ouch)

Here's a classic knowledge representation problem, in fact. In order to
respond sensibly to each object in the game that might be given to Joe,
the coder has to sit down and write a response for each object, _or_ try
to add properties or rules to classify responses among them. We might
use one flag to mark objects as 'possibly useful', another as 'not the
sort of thing you want in your pocket', and so on.

The problem is (as in the field of AI) that even in a limited
environment, your flags, properties and rules outweigh your objects by
a factor of several thousand or more, and you still don't have enough
information to discuss or manipulate the objects in any fashion that a
moron wouldn't find too basic.


(Hmm..160-something lines already. I'll post this chunk as is. Lemme
know if you want more of it)

Carl D. Cravens

unread,
Dec 30, 1995, 3:00:00 AM12/30/95
to
On 29 Dec 1995 23:38:59 GMT, dan...@brisnet.org.au (root) wrote:
>
>A while ago someone posted asking why we didn't have more 'believable'
>NPCs. I made a bit of an explanatory post with regard to that, which
>appears to have fallen into the bit bucket. Since I don't keep copies of
>these things (normally), this is both rewrite and repost.

I was one who recently asked why, with all the research being done on
agents and such, our characters really haven't advanced at all. I saw
no messages in response... I figured the question was too obvious or
something.

I've saved your message for future reference... a lot of it is "obvious"
when I read it, so there isn't much to discuss. But I will address one
particular thing that you begin to conclude.

>The problem is (as in the field of AI) that even in a limited
>environment, your flags, properties and rules outweigh your objects by
>a factor of several thousand or more, and you still don't have enough
>information to discuss or manipulate the objects in any fashion that a
>moron wouldn't find too basic.

Our problem here isn't so much that the agents aren't programmed well,
but that the _environment_ isn't. Just giving items size, weight, and
bulk properties doesn't seem enough for a truly flexible agent... they
need to have temperatures, textures, colors, etc. before the agent can
be programmed to recognize and respond to those features in a general
fashion. But the problem we're going to run into is keeping track of
all of these properties when they aren't going to matter 99% of the
time. Most of our programming tasks are coding exceptions to standard
behaviour... Joe says "I don't know much about that." except for a few
specific objects which it is important for him to know about. This is
because coding up the environment and Joe to the level of "realism"
desired creates very large amounts of data that isn't important.

I don't see a point in our lifetimes where agents stop looking like
programmed machines in our games... and that doesn't bother me. But
right now, it's painfully obvious when their programs are very
simplistic. But it's also understandable... I skimmed through the last
two years worth of archives and came across a thread about programming a
bear (no verbal interactivity simplifies things) and began coding one in
TADS. Not a simple undertaking... my bear wanders a bit, sleeps when
he's tired, looks for food if he's hungry, and can identify locations
where he's found food before. But he doesn't remember much beyond that,
can't find rooms he remembers unless he's right next to them, and can't
move about in a non-random fashion. And he's a pretty big chunk of
code.

At our current level, it's possible that our only recourse is to stick
to programming exceptions... each object gets its own special response
to every reasonable action, etc.

It just occurs to me, though... Joe's looking for that picture. Why
does he have to intelligently search for it. It doesn't matter if the
Joe-code can find the picture intelligently... it only matters that Joe
appears (to the player) to be searching intelligently. It's not
necessary to tell the player the exact specifics of Joe's actions, only
that Joe appears to be searching. We don't need intelligence... only
the illusion of such. Joe finds the picture when and where it is
appropriate for the story. If the player has had a chance to move the
picture, Joe finds it based on a set of areas that are allowed or not
allowed. If you hid it in the coffee can, in the book, or in a tea
chest, he finds it. If you hid it behind the mirror, under a
floorboard, or ate it, he doesn't. He finds it when it is appropriate
to the story, or at a random point if it's not important. The GAME
knows where the picture is at and 'gives' it to Joe when the time
comes... Joe doesn't need to know how to find it.

So the question becomes not "How can we create intelligent agents?" but
"How can we make our NPC's _seem_ intelligent?"

--
Carl (rave...@southwind.net)
* I'm not lost, I'm "locationally challenged".

root

unread,
Dec 30, 1995, 3:00:00 AM12/30/95
to

A while ago someone posted asking why we didn't have more 'believable'
NPCs. I made a bit of an explanatory post with regard to that, which
appears to have fallen into the bit bucket. Since I don't keep copies of
these things (normally), this is both rewrite and repost.

There will be a couple exercises for the reader, too. Grab a pencil and
a sheet of paper.

(Ouch)

The problem is (as in the field of AI) that even in a limited


environment, your flags, properties and rules outweigh your objects by
a factor of several thousand or more, and you still don't have enough
information to discuss or manipulate the objects in any fashion that a
moron wouldn't find too basic.

Dan Shiovitz

unread,
Jan 1, 1996, 3:00:00 AM1/1/96
to
In article <HQd5wwIe...@southwind.net>,

Carl D. Cravens <rave...@southwind.net> wrote:
>On 29 Dec 1995 23:38:59 GMT, dan...@brisnet.org.au (root) wrote:
[..]

>>The problem is (as in the field of AI) that even in a limited
>>environment, your flags, properties and rules outweigh your objects by
>>a factor of several thousand or more, and you still don't have enough
>>information to discuss or manipulate the objects in any fashion that a
>>moron wouldn't find too basic.
>
>Our problem here isn't so much that the agents aren't programmed well,
>but that the _environment_ isn't. Just giving items size, weight, and
>bulk properties doesn't seem enough for a truly flexible agent... they
>need to have temperatures, textures, colors, etc. before the agent can
>be programmed to recognize and respond to those features in a general
>fashion. But the problem we're going to run into is keeping track of
>all of these properties when they aren't going to matter 99% of the
>time. Most of our programming tasks are coding exceptions to standard
>behaviour... Joe says "I don't know much about that." except for a few
>specific objects which it is important for him to know about. This is
>because coding up the environment and Joe to the level of "realism"
>desired creates very large amounts of data that isn't important.
Well, yes. Some of this can be fixed by using a more object-oriented system,
and implementing things like materials and composition of objects and such.

>I don't see a point in our lifetimes where agents stop looking like
>programmed machines in our games... and that doesn't bother me. But
>right now, it's painfully obvious when their programs are very
>simplistic. But it's also understandable... I skimmed through the last
>two years worth of archives and came across a thread about programming a
>bear (no verbal interactivity simplifies things) and began coding one in
>TADS. Not a simple undertaking... my bear wanders a bit, sleeps when
>he's tired, looks for food if he's hungry, and can identify locations
>where he's found food before. But he doesn't remember much beyond that,
>can't find rooms he remembers unless he's right next to them, and can't
>move about in a non-random fashion. And he's a pretty big chunk of
>code.

Yeah, that was my idea, I think (which I never did anything else with, of
course). Would you be willing to post the code for the bear? One problem with
simulating intelligent NPCs that I can see is having them stay active. I mean,
what do bears do in their free time? Sleep a lot? I think the thing to do is
have say six possible states (looking for food, looking for a spot to sleep,
wandering around for fun, etc), and have a formula for calculating a priority
for each (ie, the priority for "look for food" depends on how hungry you are,
and whether you're busy doing something else), and then every so often find out
what his top-priority action is and do that. I think the way to handle rooms
is like this: have the bear maintain an array of rooms he knows about. Then
there's been code posted in the past for determining the shortest path
between two rooms (I could re-post it if necessary). Modify that code to look
at his list of rooms, and pick the shortest path that only goes through rooms
he knows. That would be a reasonable approximation of it, I think. I think
the "priority system" is the way to handle a lot of stuff, including activity
of the moment, and also what food he's going to try and get. Picking food
could be determined by what's nearby, for instance, as well as how difficult it
is to get and how much the bear likes it.

>So the question becomes not "How can we create intelligent agents?" but
>"How can we make our NPC's _seem_ intelligent?"

Well, yeah. But even that's difficult, I'm afraid. (And, of course, if the
player wants to try to "break" the AI, we don't have nearly the abilitiy to
code an AI that could stop the player.)

>Carl (rave...@southwind.net)
--
dan shiovitz scy...@u.washington.edu sh...@cs.washington.edu
slightly lost author/programmer in a world of more creative or more sensible
people ... remember to speak up for freedom because no one else will do it
for you: use it or lose it ... carpe diem -- be proactive.
my web site: http://weber.u.washington.edu/~scythe/home.html some ok stuff.


Carl D. Cravens

unread,
Jan 1, 1996, 3:00:00 AM1/1/96
to
On 1 Jan 1996 00:29:14 GMT, scy...@u.washington.edu (Dan Shiovitz) wrote:
>Well, yes. Some of this can be fixed by using a more object-oriented system,
>and implementing things like materials and composition of objects and such.

As I stated it, this _is_ the problem, not the solution. Creating a
complex environment that adds over 100% overhead yet only 1% improvement
doesn't seem very effective.


>Yeah, that was my idea, I think (which I never did anything else with, of
>course). Would you be willing to post the code for the bear? One problem with

The thread was going fine until someone disobeyed the "let's use only
psuedocode so we can all participate" suggestion and posted a 'working'
bear written in his own (at the time unpublished) Lisp-based system.
The thread died right then and there... his post was the last. (Lisp is
not a very intuitive language... I've had a course in it and I couldn't
really follow how the bear worked. AND, much of the bear's
functionality was built into the system, not the bear itself.)

I'd rather not post the bear because, 1) he doesn't work very well, and
2) I don't think this is the direction we should be going in creating
believable NPCs, so I haven't worked on him any more. The illusion of
intelligence is all that's necessary... and if the player wants to
actively try to break the illusion, that's his problem, not the
designer's. As long as the player can't accidentally (through any
reasonable action) break the NPC, why try to handle all the unreasonable
responses.

I don't think it's very important what a bear does in its free time...
what is important is what the bear does when the player can see it (or
see signs of it). It may be really neat from a programmer's standpoint
to wander around and see his bear acting and interacting on its own
based on complex code. But from the player's standpoint, it doesn't
matter whether the bear is acting on complex decision-making code or a
hardwired set of instructions... as long as it acts appropriately, the
illusion is maintained.

>>So the question becomes not "How can we create intelligent agents?" but
>>"How can we make our NPC's _seem_ intelligent?"
>Well, yeah. But even that's difficult, I'm afraid.

The illusion has to be easier than the real thing. Eliza wasn't
intelligent at all, but she fooled people. Why concentrate on currently
unobtainable levels of artificial intelligence when we don't need to
(let the AI labs work on that)? We need illusion, not simulation.

--
Carl (rave...@southwind.net)
* "*I'LL* mess with Texas!" - Captain Kansas.

Jacob Solomon Weinstein

unread,
Jan 2, 1996, 3:00:00 AM1/2/96
to
rave...@southwind.net (Carl D. Cravens) writes:

>I don't think it's very important what a bear does in its free time...
>what is important is what the bear does when the player can see it (or
>see signs of it).

"Signs of it" is an excellent point. For me, many of the most effective
NPCs are the ones that you don't actually see for much of the game; in
Hollywood Hijinx, for example, occasionally overhearing somebody else
walking around the house was much more effective than actually
interacting with your mysterious rival. (Hinting at another character's
presence is also a good way of maintaining suspense.)


I could go on and on with examples--in Curses, I often find Black a more
compelling character when I'm reading his/her notes than when I'm
actually in the room with him/her. In my own Save Princeton,
I think that the dorm rooms tell make their residents more convincing
than the residents themselves do. In Theatre, you're effectively kept
apart from your oponent until the very end--and when you actually get to
interact with her, you're kept too busy to attempt to "break" her.

One exception is Edward (if I'm remembering the name correctly) in
Christminster. He's believable partly because his mind is supposed to be
on something other than the player, and we therefore don't expect too
much from him, and partly because Gareth is particularly good at NPCs.

In addition to strewing clues to a character about the landscape, then,
another way of creating an effective illusion is to handicap your NPC in
some believable way. This isn't a particularly new insight--several
people have pointed out how much easier it is to create a believable fox,
dog, or bear than a believable human.

-Jacob

Charles Gerlach

unread,
Jan 2, 1996, 3:00:00 AM1/2/96
to
jwei...@phakt.usc.edu (Jacob Solomon Weinstein) writes:

>"Signs of it" is an excellent point. For me, many of the most effective
>NPCs are the ones that you don't actually see for much of the game; in
>Hollywood Hijinx, for example, occasionally overhearing somebody else
>walking around the house was much more effective than actually
>interacting with your mysterious rival. (Hinting at another character's
>presence is also a good way of maintaining suspense.)

I agree that it helped keep suspense up in HH, however, there were those few
instances where I was headed down the dead-end corridor, heard him further
down the dead-end, and was greatly annoyed to find out that he was not
actually there, even though there was no place he could have gone.

Much like the original example of the searching NPC, just a few checks for my
location and the direction of the noise source would have helped.

-Charles

Dan Shiovitz

unread,
Jan 3, 1996, 3:00:00 AM1/3/96
to
In article <vkA6wwIe...@southwind.net>,

Carl D. Cravens <rave...@southwind.net> wrote:
>On 1 Jan 1996 00:29:14 GMT, scy...@u.washington.edu (Dan Shiovitz) wrote:
>>Well, yes. Some of this can be fixed by using a more object-oriented system,
>>and implementing things like materials and composition of objects and such.
>As I stated it, this _is_ the problem, not the solution. Creating a
>complex environment that adds over 100% overhead yet only 1% improvement
>doesn't seem very effective.
It all depends, really. Yes, if you write all this stuff for one game, don't
use it very much in the game, and discard it all afterwards, then it's not
efficient. But if you make a "physics.t" module for TADS, which includes
various sorts of materials, generic effects when they're burnt, a better
handling of weight and volume, and so on, and then use it in all your games,
as well as distributing it so everyone can check it out ... then it's
effective. And, like it's been said about WorldClass (which is vulnerable to
the same sorts of criticisms and gains the same sorts of benefits), it also
makes the author's job a lot easier, which is something to consider.

[..]


>The thread died right then and there... his post was the last. (Lisp is
>not a very intuitive language... I've had a course in it and I couldn't
>really follow how the bear worked. AND, much of the bear's

(Well, that's debatable. LISP is fundamentally different from iterative
programming languages like C, but if you're able to change your mode of
thinking it's quite nicely done.)

>2) I don't think this is the direction we should be going in creating
>believable NPCs, so I haven't worked on him any more. The illusion of
>intelligence is all that's necessary... and if the player wants to
>actively try to break the illusion, that's his problem, not the
>designer's. As long as the player can't accidentally (through any
>reasonable action) break the NPC, why try to handle all the unreasonable
>responses.

Again, debatable. IMO, intelligence is a complex enough thing that to get any
reasonable simulation of it, we can't cheat (much). And even if we do cheat
and get everything all working, adding new things to the game becomes a
nightmare of checking hundreds of special cases. Whereas if you have a more
realistic goal-based intelligence, then adding new things is relatively
painless because so much of the work is done for you already.

>I don't think it's very important what a bear does in its free time...
>what is important is what the bear does when the player can see it (or

>see signs of it). It may be really neat from a programmer's standpoint
>to wander around and see his bear acting and interacting on its own
>based on complex code. But from the player's standpoint, it doesn't
>matter whether the bear is acting on complex decision-making code or a
>hardwired set of instructions... as long as it acts appropriately, the
>illusion is maintained.

Yes, but the "free time" question is still going to arise, if the player spends
more than a dozen turns around the bear. The bear shouldn't spend all its
time eating (or looking for food) and sleeping, should it? And presumably
the player will be around during some of the time when the bear isn't eating
or sleeping. So what do NPCs do? (The answer, I expect, goes back to *always*
giving them something to do. How to do this in the bear's case, I have no
idea. Unless this is a solitaire-playing bear or something.)

>>>So the question becomes not "How can we create intelligent agents?" but
>>>"How can we make our NPC's _seem_ intelligent?"
>>Well, yeah. But even that's difficult, I'm afraid.
>

>The illusion has to be easier than the real thing. Eliza wasn't
>intelligent at all, but she fooled people. Why concentrate on currently
>unobtainable levels of artificial intelligence when we don't need to
>(let the AI labs work on that)? We need illusion, not simulation.

Weeel. I mean, it's not like our choice is "illusion OR simulation" (despite
what I've said.) Since we can't perfectly replicate the human brain in
electronic form, we're going to have to use illusion to pretend we can. It's
all a matter of how much illusion to use.

Magnus Olsson

unread,
Jan 3, 1996, 3:00:00 AM1/3/96
to
In article <vkA6wwIe...@southwind.net>,

Carl D. Cravens <rave...@southwind.net> wrote:
>On 1 Jan 1996 00:29:14 GMT, scy...@u.washington.edu (Dan Shiovitz) wrote:
>>>So the question becomes not "How can we create intelligent agents?" but
>>>"How can we make our NPC's _seem_ intelligent?"
>>Well, yeah. But even that's difficult, I'm afraid.
>
>The illusion has to be easier than the real thing.

It should be easier by several orders of magnitude, I think.

The observation that we should aim at maing NPC's seem
intelligent is extremely important. Somehow, I get the feeling that
many people, disappointed by the cardboardish NPC's of most existing
games, go to the other extreme and demand real intelligent behaviour.

But is this really necessary?

As long as we aren't trying to create a "simulationist" piece of IF
(which I suppose would require some degree of intelligent behaviour on
the part of the NPC's), we can restrict the user's interaction with the
NPC's, add assumptions, etc, to make the illusion more believable.

Writers of non-interactive fiction have been perpetrating illusions
like this for millenia. If you think of it, the characters in a novel
have no intelligence at all. They don't have to react to stimuli,
because there are no stimuli to react to; all there is is the author's
description of what happens in a lot of situations - and that is
enough to make characters lifelike, sometimes even larger than life.

Of course, it's not that simple in IF, since our NPC do have stimuli
to respond to, questions to answer, and so on, but the point is that
if we have an NPC wandering around the stage, it may not be very
realistic to have him wander about at random, but on the other hand
there need not be any intelligence behind his wanderings. It's sufficient
that his wanderings are perceived to be motivated by intelligence.

Magnus

Carl D. Cravens

unread,
Jan 5, 1996, 3:00:00 AM1/5/96
to
On 3 Jan 1996 06:03:07 GMT, scy...@u.washington.edu (Dan Shiovitz) wrote:
>It all depends, really. Yes, if you write all this stuff for one game, don't
>use it very much in the game, and discard it all afterwards, then it's not
>efficient. But if you make a "physics.t" module for TADS, which includes

But to extend WorldClass's minor problem, if it takes a P90 to achieve
less than 2 second delays between turns, it's _not_ effective, even if
it saved the programmer hours of work. The more detailed and general
you try to become, the more overhead you create... you hit the point
where 10% of your code is used 90% of the time. Meaning 90% of your
code, the stuff that handles the real-world modeling, gets used 10% of
the time. Accurate modeling isn't _necessary_... effective illusion is.

Accurate modeling would be nice, but I'm afraid it would be too tedious
to use (Even with inheritance, do you want to consider which of the
fifty flags you need to modify on every object you create?) and create
far more overhead than we can afford right now.

>Yes, but the "free time" question is still going to arise, if the player spends
>more than a dozen turns around the bear. The bear shouldn't spend all its
>time eating (or looking for food) and sleeping, should it? And presumably

Sure... but it can still follow hardwired instructions. It doesn't need
to make any real decisions based on input. If you want it to eat, the
program can tell it where to go to do so... meta-knowledge the bear
shouldn't have, but as long as it isn't counter to what the player knows
("How could the bear have known about that??") it doesn't matter.

The same for NPC's. No player expects to follow an NPC around and watch
him go to work, eat lunch, sleep, make love, etc. We aren't expected to
model the real world in that kind of fashion. The NPC need only perform
as necessary to the story... a believable-enough performance to allow
the player to maintain suspension of disbelief.

>Weeel. I mean, it's not like our choice is "illusion OR simulation" (despite
>what I've said.) Since we can't perfectly replicate the human brain in
>electronic form, we're going to have to use illusion to pretend we can. It's
>all a matter of how much illusion to use.

I think the bigger matter is how much AI do we have access to? It's
virtually zero. The AI labs can't seem to do much beyond create a cat
or kids that trade baseball cards. I think we are forced by necessity
to continue creating our illusion until something more powerful comes
along. I don't think the lack of progress in the field of IF AI has
been due to laziness or lack of exploration... I think it's because we
just haven't figured it out yet.

--
Carl (rave...@southwind.net)
* All of the REALLY GOOD taglines are 1 character too lon

Dancer

unread,
Jan 6, 1996, 3:00:00 AM1/6/96
to

Conversation and Speech

Verisimilitude. Let's shatter it a little more, shall we?

Exercise:
Make a list of intelligent-seeming responses to every possible question
someone could ask you. Alternative: Write some kind of rule to reduce
the list to a manageable-finite size (less than....10,000 say).

Now I'll ask about quantum chromodynamics, Boris Yeltsin, and if your
case of syphilus has cleared up. How'd it hold up?
(Success at this point, would probably win you several of the awards and
competitions in the AI world)

Probably, I got some version of 'huh?' for at least one of those. Now,
let's go back to Virtual Joe. We'll kindly get him out of trouble with
that miserable photograph problem, and make him the special guest corpse
in an interactive murder mystery.

Scarlett is here, smoking a cigarette.
> SCARLETT, WHERE IS JOE?
Scarlett makes a disgusted moue, and blows a smoke ring in your
direction, "Joe's dead, flatfoot. Or had you forgotten already?"
> ASK SCARLETT ABOUT JOE
Scarlett puffs at her cigarette, and recrosses her legs, "He was a fool.
I'm glad he's dead. Always thumping about in the attic. 'Looking for a
photograph'", she mocks. She grimaces slightly and flicks ash into an
ashtray. "Colonel Plum didn't like him either, and I heard them arguing
this-evening. Joe accused Plum of rearranging the attic-storage."

Not bad, really, but no better than any other IF NPC. Let's throw it a
few curves....

> SCARLETT, DO YOU LIKE BASEBALL?
> ASK SCARLETT ABOUT THE ROMAN CONQUEST OF GAUL

Okay. They're not expected to be within the game's scope, really, are
they? (But you'd be surprised at how many people _do_ expect a more
reasonable answer to these than the default 'huh?' from the character)

Let's get back within scope and ask some more tough ones:
> SCARLETT, WHERE WERE YOU WHEN JOE WAS KILLED?
> SCARLETT, WAS ANYONE WITH YOU AT EIGHT PM?
> SCARLETT, DID PLUM FEED HIS CATS AT THE USUAL TIME?
> SCARLETT, DOES GREEN OWN A CHAINSAW?

All legitimate questions, and simple enough that the average 3-4 year
old child can extract the sense of them. We'd rather not take that long
to write a game, though.

Let's try some other examples:

> RANDOM, WHAT DID OBERON SAY TO YOU IN THE LIBRARY?
> BRAND, WHY DID SHE STAB YOU?

We could try simplifying these sorts of things to 'ask random about
oberon' or 'ask brand about stabbing' or 'ask scarlett about green' or
'ask scarlett about chainsaw'.

The problem is, that the player is going to get frustrated trying to
figure out which simplifications we decided to use, and we want to avoid
giving innappropriate answer because we guessed wrong about the context
and the question format is too simple to hold sufficient contextual
information.

'Ask Scarlett about chainsaw'
Are you asking for more infomation about the grisly way that Joe was
hacked limb-from-virtual-limb? Are you asking if Scarlett owns one? Are
you asking about the photograph which has Reverend Green standing next
to Charles Manson, holding a chainsaw and a hockey mask? Are you asking
if Green owns a chainsaw?

Closing Remarks

It _is_ possible to do NPC's better than they are usually done. Usually
this isn't done. Why? Coding an NPC to seem _marginally_ less braindead
than before can take more time than the rest of the game took. You also
need about a hundred rounds or so of beta-testing before the final game
goes out. Otherwise the first player to sit down with your game will
type in something that seems perfectly legitimate, and get a lame
response, and thereafter simply treat your NPC as run-of-the-mill.

There are things you _can_ do, though. Use a goal tree:

NPC
|
Brain
|
Top Goal
|
Subgoal 1 - Subgoal 2 - Subgoal 3
|
Subgoal 1.1 - Subgoal 1.2


Each Goal/Subgoal is an object, with code on it to attempt to accomplish
a task. Before that code executes, all subgoals (contained in it) must
be complete. And so on down the line. You can put pseudo-intelligent
heuristics, environmental stimulus-response, and timed actions and
schedules. Better still, you can add behaviour and pre-conditions simply
by popping a fresh goal object into the brain, or into an existing goal
object, allowing you to expand the behaviour set without carving up code
into an unreadable mess.

Also, try to anticipate the 'states' that your NPCs will be dealing
with. 'All is well', 'In mortal danger', 'Seeing that which should not
be'. Oddly, enough, people's priorities move around and they behave
differently in these different states. So should your NPCs.

NPCs _are_ the most complex item in your game. (Unless you've coded the
control panel to an audio-vibratory-physio-molecular transport device,
perhaps, but the point still holds.) Only truly monstrous objects will exhibit
any behaviour nearly so complex as that of a relatively simple NPC. And
as such, it behooves you to spend more time on them than any other facet
of the game.


----------------------------------------------------------------------------
| dan...@brisnet.org.au || http://thelbane.brisnet.org.au/ |
----------------------------------------------------------------------------


Mark Borok

unread,
Jan 7, 1996, 3:00:00 AM1/7/96
to
In article
<Pine.LNX.3.91.960106...@gateway1.brisnet.org.au>, Dancer
<dan...@brisnet.org.au> wrote:

> Conversation and Speech
>
> Verisimilitude. Let's shatter it a little more, shall we?
>
> Exercise:
> Make a list of intelligent-seeming responses to every possible question
> someone could ask you. Alternative: Write some kind of rule to reduce
> the list to a manageable-finite size (less than....10,000 say).
>
> Now I'll ask about quantum chromodynamics, Boris Yeltsin, and if your
> case of syphilus has cleared up. How'd it hold up?

As a player, I don't really expect characters to engage in conversation
that isn't relevant to the goal of the game. It's entertaining, but
ultimately pointless (assuming this is what you're talking about). On the
other hand, to get "huh?" or "x doesn't seem interested" as a response is
both dull and unnatural. I would suggest something along the lines of, "x
gives you an entertaining but unrevealing response" or "x responds with an
abstruse witticism". The character seems more alive and "brainy" without
requiring AI. IMO the point is the story, not programming ability
(although since I don't program, that might be sour grapes on my part).

--Mark.

Jorn Barger

unread,
Jan 8, 1996, 3:00:00 AM1/8/96
to
[xposted from rec.arts.int-fiction, a group for adventure-game
designers]

I haven't seen all of this thread, but I hope people here are aware
of comp.ai.games, where it's one of the recurring topics.

A year or two ago, Dave Whitten and I started a mailinglist project to
compile a Cyc-like knowledgebase of real-world knowledge for NPCs--
the Wisdom list (or Wisdom-faq list).

We haven't accomplished a whole lot, but you can check out the archives at:
<URL: ftp://ftp.mcs.net/mcsnet.users/jorn/wisdom/ >

My own strategy is *via alife*. I want a simplified world where
characters have most of these capabilities:

- food sharing with kin
- sexual reproduction
- pair-bonding
- cheating on spouse

This set seems to me *necessary* to generate interesting stories, and
if we can get this part sorted out, adding a lot more detail should be
comparatively easy.

Here's my alternative-ai faq. There's a lot about Cyc and game AI in
the last half:

Comp.ai.imho FAQ (Version 1.5)
a short course in AI, with net-pointers
jo...@mcs.com 26 December 1995

"A just machine to make big decisions
Programmed by fellows with compassion and vision..."
Donald Fagen "I.G.Y."

A more current and better linked version of this FAQ is on the WWWeb at:
<URL: http://www.mcs.net/~jorn/html/ai.html >


--- Why comp.ai.imho? [imho = in my humble opinion]

Here's a slogan:

============ Artificial Intelligence ===========
=========== is *way* too important ==========
============ to leave to the experts!!! ===========

There used to be a sense of idealism about AI-- that it was going to be
a powerful force for the good of humanity-- but that idealism is being
squeezed out, instead, by hypocrites who crave money, status, and power.

These 'experts' have turned AI into a battle for territory, obstructing
progress, obscuring their trivialities behind impressive-sounding
jargon, and turning this fundamental, urgently important domain of
science into an exclusive club, with an artificially limited 'union
card'...

But AI is way too important to let this happen! What lies ahead for AI
isn't just fancier productivity software-- we should be looking, much
more, for a profound revolution in human self-understanding, to be
swiftly followed by a parallel revolution in human self-government... so
we shouldn't tolerate academic politics and grantsmanship!

I've pulled together this "comp.ai.imho" FAQ as an opinionated
alternative to the "comp.ai.status-quo" FAQ created by Mark Kantrowitz,
which, while an impressive piece of work (that I've pillaged freely
from), doesn't really address the needs of *AI outsiders* to find a
convenient entre to its study on the Net.

I don't have a degree in AI, and there are many areas where my ignorance
is near-total. I'm taking a skeptical, show-me attitude towards these
areas, so if there's new technologies that haven't reached the popular
market, I'll be happy to add them onto this faq, later, once I'm
convinced of their promise.

What I know about AI was mostly worked out on my own, and then extended
and focused by three years as a programmer (and, effectively, *spy* ;^)
at Roger Schank's AI lab at Northwestern University.


-- The layout of this FAQ, and the shape of AI's past

This faq will try to embed a full range of useful net-pointers (as any
faq should) within a *readable* historical narrative of AI's history.
Briefly:

- AI's long prehistory begins with divination, then proceeds thru
Aristotle to Leibniz, Roget, and Polti-- all looking for a neat,
universal sorting of the *full range* of human experience. The primary
tools of this era were the abstraction hierarchy, and the concept of
orthogonal dimensions... imho.

- With the invention of the programmable digital computer, such *neat
systematizations* began to promise a whole new level of payback. One
conceptual hurdle to be crossed, though, was the transition from
arithmetic computation to symbolic computation, most notably via the
invention of the LISP language. LISP's dramatic (imho) history will be
explored.

- An early goal of AI research was automated translation between natural
languages (eg, Russian to English). One line of research has focused on
parsing the grammatical (syntactic) structure of sentences (basically a
pattern-matching problem), another on representing the meanings, or
semantics (that bigger problem that dates back to Aristotle). Emacs and
SGML are useful tools for thinking about these problems. Current
grammar-checkers and text-adventure games, poor as they are, may
adequately represent the state of the art in these areas... imho.

- AI is prone to collective 'manias', regarding 'magical' hardware
solutions like parallel processing, LISP machines, neural nets, etc.
***TANSTAAFL*** ...imho. It's also prone to being poisoned by ego and
greed, because of the combination of low standards and high stakes...
again, imho. [***There Ain't No Such Thing As A Free Lunch]

- *Expert systems* are AI's greatest success story, but so far their
construction has normally been a one-off affair-- each one must be built
from scratch by a labor-intensive process of 'knowledge extraction' and
knowledge representation. The CYC project is trying to fix this by
building a huge, universal expert system by 'brute force'. From a
programmer's point-of-view, though, the laying out of the data
structures is the important thing-- the algorithms of logical expertise
are comparatively trivial. And while CYC is the most ambitious attack
ever on the 'Aristotle problem', it offers as yet few breakthrus on the
problems of representing human mental (and emotional) states... (imho).

- The natural way to represent these mental states, and their laws, is
in the form of *stories*. The Aristotle-problem turns out to require a
universal inventory of human stories, following the groundwork laid out
by Polti and, surprisingly, James Joyce. A new data topology, that
unites the concept of the abstraction hierarchy with the idea of
orthogonal dimensions, promises a new direction for story
representation... imho.

- One application for AI, near and dear to most of us, is netnews
message filtering. Another, related one might be called "object-
oriented word processing", where the 'objects' include words and
phrases, concepts and stories. Designing intuitive software interfaces
also has an important AI component... imho.

- The ancient goal of self-contained robots with videocamera-eyes is
still a long way off. A simpler form of robotics research focuses on
moving virtual robots thru *simulated* worlds. Games like SimCity are
state-of-the-art simulations. Along related lines, *planning* algorithms
have tended to emphasize exhaustive combinatoric search, which is
*hopeless*... imho.

- Discussions about consciousness and pain and the ethics of
artificially-created intelligences... *bore me silly*! They're
premature, at best, and at worst, neurotic... imho!


-- The prehistory of AI

Strangely enough, the first recorded human attack on the problems of AI
came from the *fortune tellers*. If their systems for generating
predictions had overlooked certain classes of human events, then
obviously those systems could never even *accidentally* predict them...

Beginning before 1000 BCE, astrologers were already exploring an
especially rich (though arbitrary) system of planetary relationships
with three orthogonal dimensions (planet, sign, and house), trying to
map them onto human experiences. The I Ching, slightly later, explored
the 64 precise permutations of a six-bit binary system, as well as the
eight three-bit half-words they contained. The Kabalah and Tarot
offered simpler systems around 1000 AD, tied more directly to particular
human meanings like virtue and vice.

"Orthogonality" is a critical concept in software design. The name
implies a set of *dimensions* that are at 'right angles' to each other,
so that a concept can be defined in terms of one-value-for-each-dimension.
The most vivid example I know of was when MacPaint first appeared,
allowing one to easily vary the following orthogonal dimensions for each
graphic 'object': shape, size, position, fill-pattern, border-thickness,
and border-pattern.

The beauty of orthogonality in software design is that it allows an
*extremely* broad range of objects to be defined with a minimal set of
parameters. Consequently, one need only remember these few commands
to master all the objects so created. ("An ounce of orthogonality is
worth a *ton* of 'added-features' tinsel.") And the programming-code
required to implement them is also minimized! So the dream of an
orthogonal analysis of all natural and social phenomena, is an enticing
one...

Aristotle made a much more *grounded* assault on the range of human
meanings around 300 BCE. Aquinas later extended Aristotle's analysis to
include Christian ethics. The Middle Ages brought Raymond Lull playing
mystical combinatorial 'games', leading eventually to Leibniz's (1646-
1716) dream of a purely rational culture, where all concepts will have
been encoded as mathematical formulae, and philosophical disputes will
be met with the cry, *Calculemus*... "Let us calculate!"

Giambattista Vico in his "New Science" (1725, pars 161-162) was likely the
first to anticipate a universal dictionary of *concepts*, realized in 1852
with Peter Mark Roget's Thesaurus. The Dewey Decimal System (1876) and
Library of Congress Classification are two later evolutions, but all of
these are plagued by redundancies and ambiguities. Two net-specific
proposals are Yahoo's WWWeb index, and the Usenet hierarchy itself.

A.I. views *hierarchies* as networks of 'nodes' connected by 'isA links.'
In computer memory, any clump of data can be a node, and any *pointer* to
such a clump can be a link. 'IsA' is the particular relationship between
a more-specialized and a less-specialized form of the same thing: "hunger
isA motive" translates as: "Motive is a general class that includes hunger
as one specialized form." (Another common sort of link is 'partOf'.)

While hierarchical thinking comes naturally to most people, the
implementing of hierarchies in computer memory allows one to extend the
hierarchy-structure in ways that are less intuitively obvious. It's cheap
and easy, for example, to allow a single element to be 'multiply indexed'
at more than one location in the hierarchy... but even this minor tweak
comes only slowly to human thinking-habits.

-resources-

(I expect I'll turn up some Net resources on divination systems,
eventually. There's an I Ching for Unix somewhere, I'm sure...)

For Lull and his lineage, see Frances Yates, "The Art of Memory".

Roget's 1911 Thesaurus is available by anonymous FTP from the Consortium
for Lexical Research: clr.nmsu.edu:/CLR/lexica/roget-1911 [128.123.1.12]
Project Gutenberg also has Roget's 1911 Thesaurus, and many other
classics. The Project Gutenberg archive is at
mrcnext.cso.uiuc.edu:/pub/etext/
or: src.doc.ic.ac.uk:/literary/collections/project_gutenberg/
The Online Book Initiative maintains a text repository on ftp.std.com

Fritz Lehmann (fr...@rodin.wustl.edu) is collecting a master-list of
indexing schemes, or "concept systems", that currently numbers over 150
entries, many *extremely* obscure. ;^/

The Usenet hierarchy can usually be examined on Unix systems via:
/usr/lib/news/active or /usr/lib/news/newsgroups


-- LISP and symbolic computation

Writing elegant programming code is a really hard task! Designing
algorithms and data structures requires such a difficult sort of
analytic thought, it's a wonder anyone can do it well, at all. The main
barrier to AI is the need to innovate new ways of thinking about
programming-- such as object-oriented design, and declarative code.
(Jargon is the greatest enemy of the required clarity of thought!)

(Briefly, object-oriented design recognizes that each type of data-
object-- number, character-string, database record, text document,
etc.-- has its own set of properties and 'verbs' that the programmer must
define. This definition of a 'type' can be called a 'type object'.
Declarative languages like Prolog try to free programmers from thinking
about what specific sequence of actions the computer will go thru,
allowing them instead to spell out a series of 'declarative' statements
that the computer is then able to determine the sequence from.)

The LISP language was invented by John McCarthy in 1958, to simplify the
handling of arbitrary lists of arbitrary data objects. LISP builds
(almost) everything out of "cons cells", an elegant structure consisting
of two memory locations, and nothing else. These may hold pointers to
other cons cells, or to numbers-- and these numbers may represent
quantities, or *qualities, concepts, symbols*. Out of these simple
building blocks, patterns of data can be constructed that embody real-
world intelligence.

The basic task of a LISP program is to wander along a straight chain of
cons cells, pointer to pointer to pointer, looking for some pattern in
the other half of the cell. LISP-code represents these chains very
elegantly by enclosing them in parentheses:

(pattern1 pattern2 pattern3 ... )

This crawl-and-compare strategy is the normal approach to *search*, but
search is an aspect of computation that should be minimized, because it
necessarily proceeds relatively slowly. Speed gains require that data
be *sorted*, again, into neat systematizations, accessible via an
*indexing system*. (Hash tables are a poor compromise, allowing at best
the fastest possible search in cases where systematic indexing is
impossible.)

LISP is cleverly designed to allow a great deal of flexibility in
incremental program modification, and for this reason it's much favored
by symbolic AI researchers. But it's not very efficient, and it may
foster a sloppy attitude towards economical coding. The early
successes of expert systems developed in LISP led to a sudden influx of
venture capital, starting around 1980, into companies developing
dedicated LISP hardware, a financial 'bubble' that had collapsed by
1988, as expert-system development moved on to C, and competitive LISP
compilers became available for general-purpose microcomputers.

Slight differences of 'dialect' in the many different early LISPs led
to severe problems translating applications between computer platforms.
To solve this, an impressive 'Common LISP' standard was hacked out, by
committee. An object-oriented extension to the Common LISP standard is
called the Common LISP Object System (CLOS, often pronounced CEE-loss).
The 'meta-object protocol' problem for CLOS remains under debate: what
sorts of information should type-objects (etc) know about their objects,
and how should it be accessed?

Another direction LISP might yet evolve in will be to supplement its two-
element cons cells with *eight-element* cells, for building well-
balanced content-addressable hierarchies. (See below)

-resources-

GNU Emacs is a fully programmable word processor written in 'elisp', and
can make a useful development platform for many sorts of text-oriented AI
research. Gnu Emacs is available...
A Mac version is now finally available at:

A free LISP for DOS machines is...
A Lisp FAQ is also available by anonymous ftp, from the same ftp
locations as the comp.ai.status-quo FAQ (see biblio at end)
There's a comp.lang.lisp newsgroup.
Steele's beautifully-written text is the standard reference for Common LISP.
It's now available on the WWWeb.

John McCarthy, net curmudgeon, can usually be found on rec.arts.books.


-- Natural language translation, natural language processing (NLP)

On first thought, you'd expect that a *dictionary of word-substitutions*
ought to take us the best part of the way to comprehensible translated
text. In fact, though, any brief test of this idea shows it to be
massively undermined by two difficulties: 1) many idiomatic phrases
don't work at all the same in literal translation (eg, "I give you my
word"), and 2) the largest percentage of words allow several entirely
different meanings. AI researchers' first bouts with this took place
between 1956 and 1966, when the ALPAC report killed (for the time being)
all government funding for translation research.

A slightly more evolved approach focuses on 'parsing' the syntactic
structure of each sentence (ie, constructing a sentence-diagram) as a
way of disambiguating shades of meaning, by eliminating (at least) those
shadings that imply an impossible part-of-speech. This school of
thought continues to try and add more and more complex algorithms for
finding more and more subtle syntactic patterns... but less effort has
been put into trying to collect a huge dictionary of the (idiomatic)
patterns themselves, probably because the latter task de-emphasizes the
element of 'programmer macho' (a factor that steers research directions
much more than it ought!).

The poverty of current NLP can easily be seen by exploring the pathetic
grammar-checkers offered, eg, with Microsoft Word! The minimalist
parsers familiar from Infocom-style text-adventure games offer about as
much grammatical sophistication as one should expect from algorithms
alone. Several toolkits for adventure-game development are available on
the Net, allowing one to experiment with parsers and their limitations.
Front-ends for databases are another target-domain for parser research--
reducing the amount of structure required in "structured query
languages".

Emacs, with its facilities for 'grepping' complex patterns expressed as
'regular expressions', is another useful tool for NLP experiments.
Griswold's text languages, SNOBOL and Icon, are similarly useful.
Another direction is offered by SGML, TEI, and HTML, three related
projects exploiting additional layers of 'markup' within text documents.
Automated document analysis can be given an easy boost if the creators of
the documents add some signposts to the content via SGML markup.

The Text Encoding Initiative (TEI) has been working out detailed
conventions for marking up various classes of literary text, using the
Structured Generalized Markup Language (SGML). SGML markup looks like
<emphasis>this</emphasis>. The HyperText Markup Language (HTML) is an
extension of SGML to support hypertext linkages within and between
documents, and has gained great success via the WorldWide Web project.

The first round of *speech-understanding* research was funded by DARPA
until 1976, when it became clear that no quick solution was emerging.
The state of the art is still limited-vocabulary-spoken-by-a-single-
user, and probably can't do better until improved language-understanding
allows the software to *predict* which words are likeliest. An accurate
mechanical model of speech production would help, too. Handwriting
recognition has done a little better, since the time-path of the stylus
can now be tracked, but again the big improvements depend on word-
prediction.

One important subfield of NLP ought to be focusing on the meanings
(especially the emotions) carried by rhythms and tones in ordinary
speech-- "prosody". I don't know how far this has gotten-- "Sentics"
by Manfred Clynes was an interesting half-baked first attempt.

Natural language *generation* is largely the domain of ELIZA (1966,
Weizenbaum and Colby) and RACTER (1984, Etter and Chamberlain). The
annual Loebner competition for such programs, the closest thing to a
real "Turing test", was won in 1992, 93, and 95 by Joe Weintraub's PC
Politician and PC Therapist. The remarkable thing about these efforts
is their occasionally uncanny successes at mimicking intelligence,
despite absurdly primitive knowledgebases. Thom Whalen's 1994 winner
uses a very different, and promising approach.

-resources-

comp.ai.nat-lang newsgroup
The standard text on NLP is James F. Allen's "Natural Language
Understanding", Addison-Wesley 1988 (A new edition is imminent.)

WordNet, a richly interconnected hyper-thesaurus experiment, is
available by anonymous ftp from: clarity.princeton.edu:/pub/

rec.arts.int-fiction is a newsgroup for adventure game programmers.
The text-adventure archives are at: ftp.gmd.de in /if-archive/
TADS is the most popular platform.

For emacs, see above.
Icon for the Mac is available at: cs.arizona.edu
in
/icon/library/bipl.hqx (the icon program library--sample procedures
/icon/library/info.hqx and programs)
/icon/packages/macintosh/met.hqx (the executables of Icon)

Newsgroup: comp.text.sgml
To subscribe to TEI-L and get an index of the available files, send
electronic mail to the address: LISTSERV@UICVM or List...@uicvm.uic.edu
containing these two lines:
subscribe TEI-L [your name spelled out normally]
index TEI-L

comp.infosystems.www

CORPORA is a mailing list for Text Corpora. It welcomes information and
questions about text corpora such as availability, aspects of compiling
and using corpora, software, tagging, parsing, and bibliography. To be
added to the list, send a message to corpora...@x400.hd.uib.no.
Contributions should be sent to cor...@x400.hd.uib.no.

comp.speech

"doctor.el" is an implementation of Eliza that comes standard with
GNU-Emacs. Invoke it with "M-x doctor". "M-x psychoanalyze-pinhead" is
also amusing, pitting Eliza against Zippy the Pinhead.

AI_ATTIC is an anonymous ftp collection of classic AI programs and other
information maintained by the University of Texas at Austin. It
includes Parry (hi, Kibo!), Adventure, Shrdlu, Doctor, Eliza, Animals,
Trek, Zork, Babbler, Jive, and some AI-related programming languages.
This archive is available by anonymous ftp from ftp.cc.utexas.edu
(bongo.cc.utexas.edu, 128.83.186.13) in the directory /pub/AI_ATTIC. For
more information, contact attic...@bongo.cc.utexas.edu.

For a FAQ on RACTER, try ftp.mcs.com in /mcsnet.users/jorn/racterfaq.txt


-- Hardware (& other) manias: Parallelism, neural nets, LISP machines,
etc.

Speed increases in hardware are great, but they're not AI. Parallelism
and neural nets allow some new implementation strategies, but don't
begin to solve the "Aristotle problem".

Neural nets timeline:
1959: Frank Rosenblatt introduces Perceptron
1969: Minsky & Papert's book "Perceptrons" kills funding for neural net
research, apparently unjustly
1970: SciAm articles on Conway's Game of Life (cellular automata)
1975: Cooper & Erlbaum found Nestor to develop neural net technology
1982: John Hopfield resuscitates neural nets

These hardware manias are one form of a more general problem plaguing
AI, caused by the unfortunate combination of very high stakes
(especially DARPA grant money), and a very immature domain, in which
bold bluffing can take you far. "Citation inflation" is another
symptom-- concealing your poverty of ideas behind an imposing
bibliography.

Another problem is a tendency to reify programming abstractions. One
antidote to this is to make a practice of contemplating one's program
structures as pure *topologies*, with all symbolic labels stripped off.
Old topologies with fancy new names are less than worthless, compared to
entirely new topologies!

-resources-

comp.ai.neural-nets newsgroup

"Who's munging the hacker ethic?" is a short essay reflecting on some of
the 'pathologies of scientific communication' apparent on comp.ai. It
can be ftp'd from ftp.mcs.com in mcsnet.users/jorn as "munging.us"


-- Expert systems and CYC

The history of AI has shown a gratifying series of successes in the
realm of expert systems, all thru the 60s, 70s, and 80s.

The idea of expert systems is that expertise involves *logical*
thinking, and can be modelled by compiling lists of logical propositions
and performing logical transformations upon them. This might be called
the "Euclidean (or geometric) model", implying a small set of axioms
from which a wide range of theorems are then generated.

An alternative view might be called the "proverbs model". By this view,
natural selection, over the course of geologic eons, has introduced
millions of genetically-programmed *details* into the human nervous
system, anticipating particular sorts of survival-challenges that may
arise, and venturing effective ways of reacting to them. Compared to
Euclid's geometry, there will be many more 'axioms' and relatively fewer
'theorems', so the *logic* will probably be comparatively trivial--
almost all the expertise will be in the data structures (and their
contents). So once again, the Aristotle-problem is the real hurdle to
expert-system development-- how do you concisely represent *knowledge*
in a computer memory?

The Japanese Fifth Generation Project between 1982 and 1992 failed in
its goals largely because it focused on logic, eg by choosing Prolog
over LISP as its implementation language (a choice that may have been
simple anti-Americanism, since Prolog was developed by the French).

Doug Lenat's CYC (from enCYClopedia) Project at MCC in Austin, a ten-
year $35 million project begun in 1984, uses logic, too, but emphasizes
the Aristotle-problem, employing a dozen 'ontological engineers' to
enumerate tens of millions of common-sense facts that will ultimately
'add up' to logical intelligence. Lenat's goal is a system that can
understand and speak ordinary language, and detect violations of common
sense as readily as humans can.

As of 1994, CYC's sponsors were: Apple, Bellcore, DEC, the DOD, Interval,
Kodak and Microsoft. Versions of CYC for Macs and Suns are supposed to
be available now, but have enormous requirements for RAM and storage.

Lenat has revised his estimate of the total number of 'rules' required
for this, upward by a factor of ten (to 20-40 million), and extended the
time needed by another ten years. It bothers me a lot that the sort of
thing being added apparently includes rules like, "A creature with two
arms probably has two legs." This seems out-of-control to me. CYC's
ontology includes abstractions like:

Thing
Intangible
IndividualObject
Event
Stuff
Process
SomethingExisting
TangibleObject

The Text Adventure Development System (TADS), by contrast, offers the
following, much more pragmatic, partial object hierarchy:

Thing
Item: vehicle, surface, lightsource, key, food, container, clothing
FixedItem: switch, dial, button, decoration, actor, chair
Room

CYC's data-objects offer such slots as: instanceOf, inverse,
makesSenseFor, entryIsA, specSlots, slotConstraints, becameTrueIn,
qualitativeValue, sufficientCondition. One must expect that some of
these slots will ultimately have thousands of fillers, requiring hash-
tables and slowing processing proportionately, and that some objects
will have thousands of slots, causing similar problems. Interestingly,
in a recent interview Lenat claimed that the number of *facts* has been
at a plateau lately, even as the amount of useful knowledge continues to
grow, because various redundancies in the representation are also being
detected and repaired.

Lenat, at some point, asked John McCarthy to take a shot at enumerating
the laws of human emotion, a critical challenge for the project as a
whole. I don't know where this led (although Lenat claims CYC now 'knows'
about emotions), but McCarthy could have done worse than to start with
Andrew Ortony's dimensional analysis of emotions. Ortony's classes of
emotion:

Emotions about things: liking, disliking.
Emotions about persons: approving, disapproving.
about self: pride, shame.
about others: admiration, reproach.
Emotions about events for self: pleasing, displeasing.
for other: gloating, pity, resentment, happy-for.
about events in the future: hope, fear.
realized (positive): satisfaction, relief.
realized (negative): disappointment, fears-confirmed.
Emotions about another person's role in events: gratitude, anger.
about self's role: 'gratification', remorse.

Another admirable style of 'Aristotelian' thinking about whole systems
can be found in an obscure anthropology text called "Man's Place in
Nature" by C.F. Hockett (McGraw-Hill 1973). Hockett is a fearlessly
original thinker, always striving to find the *apt generalization*
behind the variations of cultures in history. For example, a series of
generalizations about techniques of primitive peoples for strengthening
the surfaces of their artifacts is characterized with the motto:
"Save the surface and you save all." (This is AI at its best!)

-resources-

comp.ai.shells newsgroup
The Expert Systems Shells FAQ is also available by anonymous ftp from
the same ftp location as the comp.ai.status-quo FAQ (see biblio at end).

CYC/MCC's presence on the Net is unfortunately very low-profile. There
was an excellent Nova (?) program about it, in a series on the computer--
"The Machine That Changed The World".
Here's some periodical references, and the only book so far:

"CYC" AI Magazine 7(1), 1986
"When will machines learn?" Machine Learning, Dec 1989
"Cyc: Toward Programs With Common Sense" CACM, Aug 1990
"Knowledge and Natural Language Processing" CACM, Aug 1990
"Common Sense and the Computer" Discover magazine, Aug 1990
"Cyc: A Mid-Term Report" AI Magazine, Fall 1990
"The commonsense reviews" Artificial Intelligence, 61(1), 1993
"CYC-O" Wired magazine, Apr 1994
"Enabling agents to work together" CACM, 37(7), 1994
Douglas B. Lenat and R.V. Guha, "Building Large Knowledge-Based
Systems" Addison-Wesley 1991

Andrew Ortony, Clore and Collins: "The Cognitive Structure of
Emotions" (about $12 paper from Cambridge U.P.)
An implementation of this theory as an a-life microworld is described
in: Elliott: The Affective Reasoner (the TaxiWorld thesis). It can be
ordered for a few dollars from ILS Tech reports, 1890 Maple
Avenue, Evanston, IL 60201.

The brand-new "Wisdom FAQ" mailing list (wisdom-...@mcs.com) is a
first stab at an Internet version of the CYC project, aimed at creating
a comparable public domain knowledgebase especially for interactive
fiction (IF) and social simulations. Its archives are at ftp.mcs.com
in mcsnet.users/jorn/wisdom/.


-- Understanding human behavior via *stories*

The basic data structures in AI might be the *rule*, the *frame*, and
the *script*... but from a programmer's point-of-view these are really
interchangeable-- just arrangements of pointers in memory-space. So the
real challenge is to discover which *interpretations* of these various
arrangements of pointers best match the way human thinking works.

"Case-based reasoning" (CBR) tries to identify nodes with 'cases'-- often
actual realworld events that could (theoretically) be described to any
infinite level of detail without being exhausted. A case is thus
approximately equal to a *story*. But this sort of thinking, again,
comes very hard to conventional computer hackers. If a story is
infinitely complex, for example, how can it be indexed as *more similar*
to some stories than others? (The solution to this paradox requires that
we recognize some details within a story as *more significant* than
others-- an importance-ranking.)

In 1900, a French literary critic named Georges Polti published an
analysis of literary plots entitled "The 36 Dramatic Situations"
(reprinted 1977 by The Writer Inc, $8.95). Polti also further subdivided
each of the 36 (citing particular plays and novels that embodied each
variant), and included for each an enumeration of the basic 'elements'
needed for the plot, eg for Supplication: "The dynamic elements
necessary are: a Persecutor, a Suppliant and a Power in authority, whose
decision is doubtful"

Here's a very rough re-sorting of Polti's thirtysix, according to a
preliminary reworking of those elements:

person thing: Obtaining
person motive: Victim of misfortune, Disaster, Ambition
person motive motive: Self-sacrifice for an ideal
person motive modality: Daring enterprise, Remorse
person modality: Enigma, Madness, Fatal imprudence, Faulty judgment
person person: Revolt, Familial hatred, Family rivalry, Conflict with
a god, Loss of loved ones
person person place: Recovery of a lost one
person person place place: Pursuit, Abduction
person person motive: Supplication, Victim of cruelty, Rivalry between
superior and inferior, Crimes of love, Deliverance
person person modality: Kinsman kills unrecognized kinsman, Obstacles
to love, Mistaken jealousy
person person motive motive: Revenge, All sacrifice for passion,
Sacrifice of loved ones, An enemy loved, Self sacrifice for kindred
person person motive modality: Involuntary crimes of love, Discovery
of dishonor of a loved one
person person person: Adultery, Murderous adultery
person person person person motive motive: Vengeance by family upon
family

Folklorists Vladimir Propp and Stith Thompson offered alternate
approaches to the story-indexing problem, but Polti's remains the most
useful for AI researchers, because (unlike Propp) it was constructed
empirically ("bottom up") by surveying literature, and (unlike Thompson)
it offers a manageable set of classes.

Abelson et al, at Yale, introduced the concept of scripts in "Scripts,
Plans, Goals, and Understanding" in 1977. That book also recapped a
primitive vocabulary called Conceptual Dependency (CD) notation,
consisting of the following verbs: atrans, ptrans, propel, move, grasp,
ingest, expel, mtrans, mbuild, speak, attend. While this proposal was
far too simplistic to work, it has tenaciously dominated the field ever
since (not to say sinisterly).

James Meehan's Yale thesis on his CD-based story-generation program
"TaleSpin" was published as "The Metanovel" (Garland, 197?) and includes
a hilarious chapter on the surreal stories that TaleSpin 'wrote' while
being debugged. Later work in this Abelsonian school proposed a clumsy
structure called a MOP (memory organization packet), then later (at
NWU's ILS) a mulligan-stew called the Universal Indexing Frame.

The original programmer for the UIF (yours truly) was inspired, after
wrestling at length with it on a low, data-structures-and-algorithms
level, to envision a much more elegant structure he later named a
"fractal thicket". (Unhappily, when he asked to present this idea to
the lab, he was terminated!) The fractal-thicket data-structure is
built on top of a simple abstraction hierarchy, each node of which can
contain a (self-similar) image of the whole hierarchy (and on and on,
as deep as one needs). This allows one to choose an arbitrary *set* of
hierarchy-elements, and represent this entire set as one single particular
node, as for example "person person place place" above. This could be
neatly implemented with the 'eight-element cons cells' described above,
so that sparsely populated regions never need to be instantiated in full.
And such a structure will minimize the necessity for *search*, effectively
substituting detailed *indexing*.

Another implication of this proposal is that anyone trying to represent
knowledge can easily take their abstraction hierarchy, two elements at
a time, and analyse these pairs for 'semantic content'. The first
question to ask of such a set is, what are the *basic relationships* of
these elements to each other? And these basic relationships should also
form a natural *story sequence*. For example, the two-element combination
"person thing" might imply the following *chronology of relationships*
between a typical person and a typical thing:

person thing: wants, makes, acquires, uses, maintains, changes,
disposes, destroys

There's a deep correspondence between these dyadic 'relationships' and
what Minsky's frame-theory calls 'slots'. In fact, looking at it this
way we should expect frames to suffer from a "Minsky bottleneck"-- an
inevitable tendency to bog down under *thousands* of slots, corresponding
to every possible relationship the object can participate in. One logical
solution is to *sort* the slots, by the *types* of their fillers... which
is just another way of describing a fractal thicket!

The more-complex *three-element* set "person person thing" will
certainly imply, among other stories, the obvious "gives" and "takes"
and "contests".

And relationships themselves can be in relationship to each other:

relationship relationship: enables disables while causes followedBy etc

Here's a (tentative) further unpacking of one of the Polti-groupings
above, for "person person motive":

Supplication: person asks person for motive
Victim of cruelty: person causes (person suffers motive)
Rivalry between superior and inferior: (person1 over person2) and (person1
gratifies motive) and (person2 suffers motive)
Crimes of love: person indulges motive towards person

Person, place, and thing are obvious, familiar, basic categories.
Motive and modality are somewhat less familiar:

thing: food tool weapon vehicle clothes bodypart etc (cf TADS)
motive: food safety sex esteem family self-expression etc (cf Maslow)
modality: real imaginary desired possible feared etc (cf Ortony)

The person-motive realtionships:

person motive: suffers abstains denies gratifies indulges etc

form a sort of mythic chronological sequence that I call the *pride
cycle*. It forms the basis for James Joyce's universal inventory of
story-elements, "Finnegans Wake" (1939). Joyce's earlier novel, "Ulysses"
(1922) was a preliminary sorting of the universe of story-elements into
18 chapters, derived from episodes of Homer's Odyssey, which Joyce
considered to be the most well-rounded portrait of an everyman, ever in
literature. The 18 chapters cover a single day in the life of a humble
Dubliner named Leopold Bloom. In order to pack every sort of story into
Bloom's day, Joyce transforms them *via metaphor* into completely mundane
everyday details. Analysis of Joyce's AI here has barely been begun by
scholars, who have further tended to dismiss FW as a perfectly baffling
mystery.

Joyce, an avowed Aristotelian who is known to have owned Polti's book,
found it necessary in his work to challenge fearlessly all the *taboos*
of the literary censors. Anyone who tries to inventory the whole range
of the human experience must follow Joyce here, and this requires a
level of self-honesty that has never been emphasized in AI research!

-resources-

The ILS tech report about the UIF, and others, can be ordered for a few
dollars from ILS Tech Reports, 1890 Maple Avenue, Evanston, IL
60201.
Schank & Osgood et al: A Content Theory of Memory Indexing [UIF]
Schank & Fano: A Thematic Hierarchy for Indexing Stories [another try]
Kolodner & Jona: Case-Based Reasoning: an overview [simple and clear]

ftp ftp.mcs.com
cd mcsnet.users/jorn
get README.jb |cat
get ilsmemoir.txt [intro to AI, for game designers, written as a memoir]
get thicketfaq.txt [intro to fractal thicket indexing]
get diykr.txt [do-it-youself knowledge-representation, very short]
get aijoyce.txt [intro to Joyce for AI types]
get joycefaq.txt [intro to Joyce for literary types]
get storymath.txt [intro to AI for Joyceans]
get fwdigest1.txt [100k analysis of FW chapter 4, paragraph 1]


-- Message filtering, object-oriented word-processing, software design

The netnews hierarchy encourages a very high level of pre-sorting among
postings. Killfiles can supplement this, inefficiently. The newsreader
'strn' is the current state-of-the-art in complex killfiling. To go
beyond this will probably require that posters 'tag' keywords, and also
that a system for message-rating be agreed to.

The next stage in the evolution of word processing must be to treat
words, phrases, concepts, etc. as *objects*.

Interface design might be transformed by analysing the *tasks* the
software will be used for, and having the software use this analysis
to anticipate the user's needs. (Current software offers instead
many 'micro-commands' that the user must combine into sequences,
or at best into 'macros'.)

-resources-

news.software.readers

Some specs for an object-oriented word processor are available at
ftp.mcs.com as /mcsnet.users/jorn/decentwrite.txt

The students.chi mailinglist is dedicated to the Human-Computer
Interaction field, focusing on the research, design, development and
evaluation of human-computer communication and interaction. The ii.chi
mailinglist is more specifically about intelligent interfaces.
To be added to either, send a request to Nick Briggs at
"Regist...@xerox.com". (I have no direct knowledge of this list!)


-- Vision, robotics, planning, simulation and artificial life

Some miscellaneous related topics:

Human vision must work, in part, via the imagination-- the mind
projecting multiple possible images of the future (or the present). At
any moment, each section of the visual field must be accounted for, to
some degree, in terms of an imaginary projected image, *not at all unlike
a hallucination*. (Learning about the world means fine-tuning our
hallucinations!) This parallelism between creating images and
perceiving them might be generalized as the "AI complemenarity principle".

There's a cute book called "Vehicles: experiments in synthetic
psychology" by Valentino Braitenberg (MIT Press, 1984), that shows how
very simple electronic 'nervous systems' can allow very simple robots to
exhibit fairly interesting behaviors, like approach and avoidance. This
sort of *emergent behavior* is the ultimate goal of alife research.

There's a common fallacy that 'virtual worlds' could be built entirely
out of the basic laws of physics-- a Grand Unified Theory of
Everything-- so that the path of each particle in the world would be
traced independently, by some super-super-supercomputer doing millions
of math calculations each nanosecond. But this isn't even practical for
a billiards simulator! What's needed, instead, is an inventory of
'particle stories' (cf Feynmann diagrams?) which are *qualitatively*
distinct, which is likely how the brain itself does most of its physics
predictions. There's a famous AI paper called "The Naive Physics
Manifesto" (1978, Patrick Hayes) that broke early ground here.

Computer *planning* is in a very primitive state. The normal models
require that the computer do a thorough search of a large number of
combinations of plan-steps, looking for the most efficient one. This
might be compared to searching a large rectangular field, one row at a
time. An alternative model might be compared to a widening spiral
pattern, where the first circular pass returns some extremely coarse
proposal, and successive passes refine it further and further. The
advantage here is that in real life one may not have enough time to
complete the thorough search, so the 'spiral' model allows one to
abandon the search at any point without ending up empty-handed. This
spiral approach once again requires *prioritising* the elements of the
planning domain.

Computer gaming is the only domain of commercial software in which
programs are *routinely* evaluated for the quality of their AI-- which
in this case normally refers to the program's ability to serve as an
intelligent opponent, even to stand in for a second human gameOBplayer.
This sort of AI can be implemented as a set of possible story-cases to
be executed under certain conditions.

Here's a breakdown of the current status of computers at various human
games, compiled by Victor Allis (vic...@cs.vu.nl):

Othello: Strongest program (Logistello by Michael Buro) stronger than
strongest human players.
Checkers: Strongest program (Chinook by Jonathan Schaeffer et al.) has
now defeated the world champion
Backgammon: Strongest program (TD-gammon by Gerald Tesauro) at world
champion level.
Chess: Strongest program (Deep Thought II, by Feng Hsu and Murray Campbell)
at about the 100th-150th place on world ranking
Bridge: Strongest programs (unclear which) at amateur level
Go: Strongest programs (several, see rec.games.go) at about 8-10 kyu,
which is a little above novice level.

There's also a whole category of computer games devoted to *simulations*
(although flight simulators, whose AI is comparatively trivial,
consistently lead the field in sales). Maxis has done very well with
SimCity, SimEarth, SimAnt, SimLife, SimFarm, SimHealth, and A-Train.
"Civilization" is something like SimCity with inter-city wars. Games
based on economic simulations go back as far as Lemonade Stand and the
like.

Chris Crawford is the grandfather of *social* simulations, with Balance
of Power, Balance of the Planet, and Trust & Betrayal. The first of
these involves the realization that international politics is almost
entirely a question of *maintaining face* (the esteem motive). The
second, Balance of Power, shows how the interconnectedness of ecological
factors makes simple solutions radically ineffective. The third is a
very primitive first try at simulating a community of humanoid
alliances. AI-history collectors will want to get the source code for
T&B from Chris for $150:

Other interesting sims:
Hidden Agenda: you're president of a Central American country-in-crisis,
and must weigh the requests of various factions, with the help of your
fallible advisors.
Shadow President: ditto for US politics?

Carnegie Mellon has an artificial-personality/ virtual-world project
called "Oz" led by Joseph Bates.

-resources-

comp.robotics newsgroup

The most affordable robot kits so far, Hero robots from Heathkit, are no
longer available except secondhand. But for as little as $10 you can
build a six-legged walking robot called a "Stiquito", that fits in the
palm of your hand. It uses an unusual nickel-titanium alloy called
'nitinol' that directly converts the energy of a 9-volt battery into
mechanical force. You can order the kit ($10), tech report ($5), and
how-to video ($10) from:
Computer Science Dept, Attn: Stiquito/TR 363a/Video [specify which]
215 Lindley Hall, Indiana University, Bloomington, Indiana 47405
Checks or money orders should be made payable to "Indiana University".
IUCS Technical Report 363a describes Stiquito's construction and is
available by anonymous ftp from
cs.indiana.edu:/pub/stiquito/ [129.79.254.191]
Questions about Stiquito should be sent to Prof. Jonathan W. Mills
<stiq...@cs.indiana.edu>. To join the Stiquito mailing list run by Jon
Blow of UC/Berkeley, send mail to: stiquito...@xcf.berkeley.edu.

comp.ai.vision

comp.simulation
A critique of SimCity can be found in:
Paul Starr, Seductions of Sim: Policy as a simulation game, The American
Prospect 17, Spring 1994, pages 19-29.

comp.ai.alife
The basic resources on alife:
Langton, Chris G., editor, "Artificial Life" (Proceedings of the First
International Conference '87), Addison-Wesley, 1989.
Langton, C.G. et al, eds, "Artificial Life II", Addison-Wesley, 1991.
Langton, C.G., editor, "Artificial Life III", Addison-Wesley, 1994.
Steven Levy's "Artificial Life"

There's an alife mailing list at: alife-...@cognet.ucla.edu
but it may have been superceded now by the comp.ai.alife newsgroup.

CMU Oz Project:
http://www.cs.cmu.edu:8001/afs/cs.cmu.edu/project/oz/web/oz.html
Some of the project's papers are also accessible as
ftp.cs.cmu.edu:/afs/cs.cmu.edu/project/oz/ftp/papers/

Artificial Morality: artmor...@unixg.ubc.ca
This is a mailing list for discussion of Peter Danielson's book,
"Artificial Morality: Virtuous Robots for Virtual Games" (Routledge,
New York, 1992) and related issues. It explores theories of rational
morality with Prolog. To join the list, send an email message to
artmoral-l...@unixg.ubc.ca
[I have no direct knowledge of this list.]

comp.ai.games


-- Consciousness

Searle and Dreyfus and Penrose are just naive about symbolic AI. It
will ultimately succeed, to *some* extent, anyway. Their arguments are
not really insightful. (For example, Lenat claims with some justice that
CYC is already conscious, because it 'knows' that it's a computer
program and not a human... but this knowledge is, of course, just a
pointer in memory!) Pain and pleasure, though, may be a matter of
analog neural 'hardware', and may *not* be replicable by conventional
digital algorithms. (On the other hand, 'consciousness' itself may be a
neurotic illusion-- see Julian Jaynes, "The Origin of Consciousness in
the Breakdown of the Bicameral Mind", and compare it also to Zen
Buddhism's mystical goal of transcending consciousness.)

The way to deal with human *subjectivity* is to observe it
dispassionately, and describe it with the most precisely evocative
language available. Coining new words for subjective distinctions is
never a good idea-- natural language will have dealt better with the
problem, millennia ago!

-resources-

comp.ai.philosophy
alt.consciousness
alt.fan.hofstadter

PSYCHE is a quarterly refereed electronic journal concerning the
interdisciplinary exploration of the nature of consciousness and its
relationship to the brain. To subscribe, send a message with
"SUBSCRIBE PSYCHE-L Firstname Lastname" in the body to
LISTSERV%NKI.B...@cunyvm.cuny.edu.
A discussion group PSYCHE-D has also been created for discussion of
the contents of the journal and related topics. To subscribe, send a
message with "SUBSCRIBE PSYCHE-D Firstname Lastname" in the body to
the list server. The moderator of PSYCHE-D is David Casacuberta,
<IL...@cc.uab.es>. [I have no direct knowledge of these, either.]


-- Bibliography, etc.

The latest version of the 'comp.ai.status-quo' FAQ is available via
anonymous FTP from:
ftp.cs.cmu.edu:/user/ai/pubs/faqs/ai/ [128.2.206.173]
using username "anonymous" and password "name@host" (substitute your
email address) or via AFS in the Andrew File System directory
/afs/cs.cmu.edu/project/ai-repository/ai/pubs/faqs/ai/
as the files ai_1.faq, ai_2.faq, ai_3.faq, ai_4.faq, ai_5.faq and
ai_6.faq.
You can also obtain a copy of that FAQ by sending a message to
ai+q...@cs.cmu.edu with
Send AI FAQ
in the message body.
The FAQ postings are also archived in the periodic posting archive on
rtfm.mit.edu:/pub/usenet/news.answers/ai-faq/ [18.181.0.24]
If you do not have anonymous ftp access, you can access the archive by
mail server as well. Send an E-mail message to mail-...@rtfm.mit.edu
with "help" and "index" in the body on separate lines for more
information.

Cool free offer-- check this out!
The Computists' Communique is a weekly online newsletter for AI/IS/CS
scientists. It covers research and funding news; career, consulting,
and entrepreneurial issues; AI-related job postings and journal calls;
FTPable & other resource leads; market trends; analysis and discussion.
Subscriptions are fairly pricey, but it's top quality stuff. You can
get a free-sample subscription-- every fourth issue only-- by replying
to la...@ai.sri.com and asking to be added to the Full Moon distribution.

For a general overview of AI, I recommend this coffeetable book:
Raymond Kurzweil's "The Age of Intelligent Machines", MIT Press,
1990, 565 pages, ISBN 0-262-11121-7, $39.95.

The following timeline is based mostly on "The Brain Makers" by H.P.
Newquist (ISBN 0-672-30412-0), and some Kurzweil. It has been plagiarized
by Mark Kantrowitz, without credit:

1000BCE: I Ching
300BCE: Aristotle, Euclid
1617: John Napier's "Napier's Bones"
1642: Blaise Pascal's Pascaline (automatic calculating machine)
1694: Liebnitz's "Computer" can do multiplication
1725: Vico's "New Science" calls for universal thesaurus of concepts
1822: Babbage's Difference Engine (not completed)
1832: Babbage's Analytic Engine (never built)
1847: Boole's symbolic logic
1852: Roget's Thesaurus
1873: Dewey Decimal System
1890: Hollerith's punched-card computer
1900: Polti's "36 Dramatic Situations"
1922: James Joyce's "Ulysses"
1939: Joyce's "Finnegans Wake"
1940: First electronic computers in US, UK, and Germany
1946: ENIAC
1950: Alan Turing "Computing Machinery and Intelligence"
1953: Shannon gives Minsky and McCarthy summer jobs at Bell Labs
1956: Rockefeller funds M&M's AI conference at Dartmouth
1956: CIA funds GAT machine-translation project
1956: Newell, Shaw, and Simon's Logic Theorist
1957: Newell, Shaw, and Simon's General Problem Solver
1958: McCarthy creates first LISP
1959: M&M establish MIT AI Lab
1959: Frank Rosenblatt introduces Perceptron
1960: Bar-Hillel deflates dreams of easy machine translation
1962: First industrial robots
1962: McCarthy moves to Stanford, creates Stanford AI Lab in '63
1963: Quillian lays groundwork for semantic nets
1963: ARPA gives $2 million grant to MIT AI Lab
1964: Bobrow's "Student" solves math word-problems
1965: Feigenbaum takes over SAIL; Noftsker takes over MIT AI Lab
1965: Feigenbaum and Lederberg begin DENDRAL expert system project
1966: Weizenbaum and Colby create ELIZA
1966: ALPAC report kills funding for machine translation
1967: Greenblatt's MacHack defeats Hubert Deyfus at chess
1969: Minsky & Papert's "Perceptrons" kills funding for neural net
research
1969: Kubrick's "2001" introduces AI to mass audience
1970: Terry Winograd's SHRDLU, minor NLP success
1970: Colmerauer creates PROLOG
1972: DARPA cancels funding for robotics at Stanford (Shakey)
1973: Lighthill report kills AI funding in UK
1973: LOGO funding scandal: Minsky & Papert turn MIT lab over to Winston
1974: Edward Shortliffe's thesis on MYCIN
1974: Minsky reifies the 'frame'
1976: DARPA cancels funding for speech understanding research
1976: Greenblatt creates first LISP machine, "CONS"
1976: Doug Lenat's AM (Automated Mathematician)
1976: Marr's "primal sketch" improves computer vision
1978: Marr & Nishihara's "2.5-D sketch"
1978: SRI's PROSPECTOR discovers molybdenum vein
1978: Patrick Hayes' "Naive Physics Manifesto"
1980: First AAAI conference at Stanford
1980: McDermott's XCON for configuring VAX systems
1981: Kazuhiro Fuchi announces Japanese Fifth Generation Project
1982: John Hopfield resuscitates neural nets
1983: MCC consortium formed under Bobby Ray Inman
1983: DARPA's Stategic Computing Initiative commits $600 million over 5
yrs
1984: Austin AAAI conference launches AI into financial spotlight
1984: Doug Lenat begins CYC project at MCC
1984-86: Corporations invest some $50 million in AI startups
1985: GM and Campbell's Soup find expert systems don't need LISP
machines
1986: Thinking Machines Inc introduces Connection Machine
1987: "AI Winter" sets in
1987: Bottom drops out of LISP-machine market due to saturation
1988: AI revenues reach $1 billion
1988: The 386 chip brings PC speeds into competition with LISP machines
1988: Schank forced to resign from Yale and Cognitive Systems
1990: MacArthur Foundation gives Richard Stallman $240,000 genius grant
1992: Japanese Fifth Generation Project ends with a whimper
1992: Japanese Real World Computing Project begins with a big-money bang
1985-present: many other expert-systems success stories

-==---
. hypertext theory : artificial intelligence : finnegans wake . _+m"m+_"+_
lynx http://www.mcs.net/~jorn/ ! Jp Jp qh qh
ftp://ftp.mcs.net/mcsnet.users/jorn/ O O O O
news:alt.music.category-freak Yb Yb dY dY
...do you ever feel your mind has started to erode? "Y_ "Y5m2Y" " no.

Magnus Olsson

unread,
Jan 8, 1996, 3:00:00 AM1/8/96
to
In article <4crbgi$d...@news.cc.brandeis.edu>,
Xiphias Gladius <i...@cs.brandeis.edu> wrote:
>I'm in the middle of playing _Christminister_ right now, and I do like
>the NPCs in the game.
>
>Yes, all of them have a canned response when they don't understand
>you, but the response makes sense for the character.
>
>Poor Edward is distraught because some horrid person smashed his
>window and his parrot escaped.
>
>The porter is virtually deaf.
>
>The Master of the college responds with, "Mmm, yes, that's very
>interesting. . ." whenever you go outside his (limited) range of
>experience.

IMHO, the first two examples are quite good ways of avoiding complex
dialogue.

I find the Master's way of solving the problem, however, to be rather
irritating. There's simply no way any real person would keep on
saying "Mmm, yes, that's very interesting" at whatever you say to him.

On the other hand, I realize that this is part of the game, so to
speak. When I play an adventure game, I accept that there are lots of
things that the NPC's don't know. I don't find it particularly hard to
suspend my disbelief in this case. Though of course it would be nice
to have NPC's with better conversational abilities...

Magnus Olsson
m...@df.lth.se

Xiphias Gladius

unread,
Jan 8, 1996, 3:00:00 AM1/8/96
to
Dancer <dan...@brisnet.org.au> writes:

> Verisimilitude. Let's shatter it a little more, shall we?

> Exercise:
> Make a list of intelligent-seeming responses to every possible
> question someone could ask you. Alternative: Write some kind of rule
> to reduce the list to a manageable-finite size (less than....10,000
> say).

> Now I'll ask about quantum chromodynamics, Boris Yeltsin, and if
> your case of syphilus has cleared up. How'd it hold up? (Success at
> this point, would probably win you several of the awards and
> competitions in the AI world)

Well, should we talk about ways to make characters respond reasonably,
or ways to make a lack of response sound reasonable?

I'm in the middle of playing _Christminister_ right now, and I do like
the NPCs in the game.

Yes, all of them have a canned response when they don't understand
you, but the response makes sense for the character.

Poor Edward is distraught because some horrid person smashed his
window and his parrot escaped.

The porter is virtually deaf.

The Master of the college responds with, "Mmm, yes, that's very
interesting. . ." whenever you go outside his (limited) range of
experience.

In Planetfall, Floyd was a limited character. He was just a silly
little robot, although a lovable one. But you didn't EXPECT Floyd to
know anything about, say, Boris Yeltsin.

For hypothetical example of this kind of coding. . .

In Front of Big Bird's Nest

You're standing on a residential dead end in New York City. You can
see a door to the north, through which you can see yellow feathers.
To the southeast is the Monster Hotel. You can see a battered trash
can to the northwest. Off to the west is an apartment house, a
storefront with a sign in it saying "Open/Apierto", and, beyond that,
a large open area with a tire swing. Off to the east is the rest of
New York.

Elmo is here.

>x Elmo

Elmo is a small cute monster covered in red fur.

>ask Elmo about kidnapping

Elmo shakes his head. "Elmo not know anything about kidapping."

[ Yeah, that would be fairly easy to code -- but that's also what he'd
say . . . ]

>ask elmo about waiter

"Grover works as a waiter at the restaurant. Grover Elmo's friend."

>ask elmo about alphabet

Elmo brightens. "ABCDEFGHIJ umm. . . K ummm. . .LMNO. . . " He
scrunches up his face in concentration. . ."P . . .QRS
. . . TUVW. . . X. . YZ! Yaay! Elmo know his ABC's!" He jumps up
and down a couple times.

>g

Elmo brightens. "ABCDEFGHIJ umm. . . K ummm. . .LMNO. . . " He
scrunches up his face in concentration. . ."P . . .QRS
. . . TUVW. . . X. . YZ! Yaay! Elmo know his ABC's!" He jumps up
and down a couple times.

[ . . . ]

Yup, simplistic, and not real believable, you may think. But ask
anyone who's watched Sesame Street -- that's how Elmo acts. . .

Another idea would be to put the questioning in a format where the
questions are necessarily limited. . .

>ask tracey about syphilis

Tracey's lawyer stands up. "Objection! I can't see how that relates
to the case!"

The judge nods. "Sustained," she says.

- Ian

Darius Katz

unread,
Jan 8, 1996, 3:00:00 AM1/8/96
to
In article <4criqv$h...@news.lth.se>,

Magnus Olsson <m...@oberon.df.lth.se> wrote:
>>
>>The Master of the college responds with, "Mmm, yes, that's very
>>interesting. . ." whenever you go outside his (limited) range of
>>experience.
>
>I find the Master's way of solving the problem, however, to be rather
>irritating. There's simply no way any real person would keep on
>saying "Mmm, yes, that's very interesting" at whatever you say to him.
>
>Magnus Olsson
>m...@df.lth.se

Considering that the man is reading a newspaper, I think it is a very
reasonable answer to get. My mom does this all the time. When I ask her
something while she is reading, she usually says something like that.

When I really get her attention, she doesn't even remember I asked her
something just a few seconds before.


Best regards,

Darius Katz
ka...@df.lth.se

Marty Stoneman

unread,
Jan 9, 1996, 3:00:00 AM1/9/96
to
Carl D. Cravens (rave...@southwind.net) wrote:

[[SNIP]]

: I think the bigger matter is how much AI do we have access to? It's


: virtually zero. The AI labs can't seem to do much beyond create a cat
: or kids that trade baseball cards. I think we are forced by necessity
: to continue creating our illusion until something more powerful comes
: along. I don't think the lack of progress in the field of IF AI has
: been due to laziness or lack of exploration... I think it's because we
: just haven't figured it out yet.

: --
: Carl (rave...@southwind.net)
: * All of the REALLY GOOD taglines are 1 character too lon

You're right about the "AI Labs"; they probably can't be much help to
your IF problems right now. At Anthrobotics, we're a private venture
which has made some really offbeat and interdisciplinary (too much for
most of academia) approaches to AI "life"; and, after reading your
threads for a while, I think it's very possible that we could help. For
now, our help to one or more of you would be kept confidential -- you
know, you would have to agree to keep our stuff confidential for a
while. Our software demo, realtime on an old slow 286 computer, has a
humanoid character "living" in an unpredictable constructed "world" --
and this character, who has emotions, plans, metabolism, etc., tells
"true" stories in English about its life-happenings and can answer
questions (restricted) about what is going on when it is "interrupted".

If you wish to give a joint project a try, including some funding on your
part after checking us out, please email (with your phone number and
address) me at

Marty Stoneman
ma...@indirect.com

Kenneth Jason Fair

unread,
Jan 10, 1996, 3:00:00 AM1/10/96
to
In article <4criqv$h...@news.lth.se>, m...@oberon.df.lth.se (Magnus Olsson) wrote:

>I find the Master's way of solving the problem, however, to be rather
>irritating. There's simply no way any real person would keep on
>saying "Mmm, yes, that's very interesting" at whatever you say to him.
>

>On the other hand, I realize that this is part of the game, so to
>speak. When I play an adventure game, I accept that there are lots of
>things that the NPC's don't know. I don't find it particularly hard to
>suspend my disbelief in this case. Though of course it would be nice
>to have NPC's with better conversational abilities...

Hmmm. Maybe NPCs should get bored and wander off after a couple of
questions. Or refuse to talk to you for a little while. You could have
an attribute, say an "annoyance index", that would increase every time
you asked that person a question but which would decay at a certain
rate as time passes. Then if you bumped up over that index, the character
would refuse to answer until you dropped back down. This could apply
for programmed responses and "I don't know"s.

For example, from Witness (I'm making up the dialog):

>ASK MONICA ABOUT PHONG
"Phong? Oh, he's been with the family for years. Dad confided in him
ever since Mom di-" She trails off.

Monica seems distressed.

>ASK MONICA ABOUT MATCHBOOK
She remains silent, shaking her head slowly.

A tear rolls down Monica's cheek.

>ASK MONICA ABOUT CAN
She remains silent, shaking her head slowly.

More tears appear in Monica's eyes.

>ASK MONICA ABOUT CLOCK
She glances left, then right. "I don't know anything about that,"
she replies.

A sob escapes from Monica's lips.

>ASK MONICA ABOUT HER FATHER
"Why do you keep asking me all these questions?" she shouts. "Just
leave me alone!"

Monica breaks down, sobbing. You'll have to wait until she calms
down to ask her more questions.

--
KEN FAIR - U. Chicago Law | Power Mac! | Net since '90 | Net.cop
kjf...@midway.uchicago.edu | CABAL(tm) Member | I'm w/in McQ - R U?
The Constitution is more than simply the words. It includes
all of the legal, political, and social history of America.

Adrian Preston

unread,
Jan 10, 1996, 3:00:00 AM1/10/96
to
: In article

: > Conversation and Speech


: >
: > Verisimilitude. Let's shatter it a little more, shall we?
: >
: > Exercise:
: > Make a list of intelligent-seeming responses to every possible question
: > someone could ask you. Alternative: Write some kind of rule to reduce
: > the list to a manageable-finite size (less than....10,000 say).
: >
: > Now I'll ask about quantum chromodynamics, Boris Yeltsin, and if your
: > case of syphilus has cleared up. How'd it hold up?

Haven't researchers been trying to do this for decades? It's called the
Turing test I believe. If, as adventure game programmers, we can succeed
where so many better minds than ours have failed, ( than mine anyway )
I will be surprised. :)

Anyway, try 'Knock knock.' to one of these intelligent response machines.

--
+----------------------------------------------------------------------+
Adi, Lecturer in ??????? | no .sig
Kingston University | no .sig
+----------------------------------------------------------------------+


Jason Thompson

unread,
Jan 22, 1996, 3:00:00 AM1/22/96
to
One way to handle 'intelligent NPCs' would be as huge a project as anything
imaginable.. (I'm just suggesing it theoretically..) You'd have to put all
the definitions and references and generally the sum of human knowledge in a
BIG database, and then each NPC would basically dip into the same 'store' of
facts in case you asked weird questions ("Why, syphilis you ask? It's a
degenerative disease...") Each NPC would only have to have a 'tone of voice'
or _style_ of speech coded ('only'... yeah, that's funny), as well as have
certain words/areas/knowledge in the database rendered inaccessible to them
(so the street thug wouldn't know about Helen of Troy, but the historian
would...) Of course, this would result in a massive many-gigabytes database
of stuff attached like a bloated parasite to a little tiny interactive
fiction game... ;) And God forbid trying to code NPCs who can learn from
experience or 'remember' past statements! Ha ha ha! Ha ha! (Although this is
more worth bothering with than the 'database' thing. Please don't flame me.
I scarcely meant it seriously.)

I do think parsers have gone downhill, though... something like the 'speech'
code in ULTIMA 4 (yes, I know it's not IF), where you can 'ask about'
things, is much more versatile than the subsequent ULTIMAs, which just used
the 'Choose-Your-Own-Adventure' style of linear conversations ('Pick
responses A, B, or C...) The important thing should be that the player FEELS
they have a wide range of choices... you have to conceal how little the NPCs
know and how tiny the world is.

Jason B. Thompson
Knygathin Zhaum


Mark Borok

unread,
Jan 23, 1996, 3:00:00 AM1/23/96
to
In article <4dvljs$j...@sonic.net>, ja...@sonic.net (Jason Thompson) wrote:

You'd have to put all
> the definitions and references and generally the sum of human knowledge in a
> BIG database, and then each NPC would basically dip into the same 'store' of
> facts in case you asked weird questions ("Why, syphilis you ask? It's a
> degenerative disease...")

In that case, why not also have your NPC's double as internet "agents"?
When asked an irrelevant question, they will simply turn on the user's
modem (if present) and do a full internet search of the topic. No need to
create a huge database, and think of the fun when, say, a medeival peasant
rattles off the name of every enzyme present in the human body.

On a different note, I've always liked the idea of a game where there is
more than one solution to a given problem. Anyone know of games like this?
I'm not too experienced, so I may have missed a lot.

--Mark.

Julian Arnold

unread,
Jan 23, 1996, 3:00:00 AM1/23/96
to
Jason Thompson (ja...@sonic.net) wrote:
> One way to handle 'intelligent NPCs' would be as huge a project as anything
> imaginable.. (I'm just suggesing it theoretically..) You'd have to put all

> the definitions and references and generally the sum of human knowledge in a
> BIG database, and then each NPC would basically dip into the same 'store' of
> facts in case you asked weird questions

This sort of thing is being done already.

There's the CYC project:

"CYC is the name of a very large, multi-contextual knowledge base and
inference engine...

...CYC presently contains approximately 400,000 significant assertions,
which include simple statements of fact, rules about what conclusions to
draw if certain statements of fact are satisfied (true), and rules about how
to reason with certain types of facts and rules. New conclusions are
derived by the inference engine using deductive reasoning.

...CYC is intended to provide a "deep" layer of understanding that can be
used by other programs (such as domain-specific expert systems) to make them
more flexible."
-- David Whitten, "The Unofficial, Unauthorized CYC Frequently Asked
Questions Information Sheet"

And the Wisdom project:

"The brand-new "Wisdom FAQ" mailing list (wisdom-...@mcs.com) is a
first stab at an Internet version of the CYC project, aimed at creating a
comparable public domain knowledgebase especially for interactive fiction
(IF) and social simulations."

-- Jorn Barger, "Comp.ai.imho FAQ"

Both FAQs are posted to comp.ai every now and then; the CYC FAQ is also
available from it's author <whi...@netcom.com>; the Wisdom archives, and
details of subscribing to the Wisdom mailing list, are at
<ftp://ftp.mcs.com/mcsnet.users/jorn/wisdom/>.
--
Jools Arnold jo...@arnod.demon.co.uk


Andrew C. Plotkin

unread,
Jan 24, 1996, 3:00:00 AM1/24/96
to
ne...@zen.khoral.com (Neil Bowers) writes:
> Mark Borok (ma...@pcix.com) wrote:
> : I've always liked the idea of a game where there is

> : more than one solution to a given problem. Anyone know of games like this?
>
> This can be further refined into two categories:
>
> 1) multiple `correct' solutions
>
> Where there is more than one solution, and no solution scores
> more, or is `better' than others.
>
> I can't think of any large examples offhand, but there are quite
> a few of the form "how to persuade an NPC to do something for you".

Curses has a few of these (opening the medicine bottle.)

> 2) one optimal solution
>
> Where there is one correct solution, further refined by:
>
> a) alternative `wrong' solutions
>
> These are often solutions which seem right short term,
> but later on are revealed as red-herrings, for example.
> For example, getting through the Guarded Door in Enchanter.
>
> a) alternative sub-optimal solutions
>
> Using such a solution does not preclude completion of the
> entire game say, but you won't get a 100% score.
> Wishbringer is an example.
>
> I think 2a is the most frequently used of these, but I don't have a huge
> experience to draw on.

The first 2a, or the second 2b? :-)

--Z

"And Aholibamah bare Jeush, and Jaalam, and Korah: these were the borogoves..."

Christopher E. Forman

unread,
Jan 24, 1996, 3:00:00 AM1/24/96
to
Neil Bowers (ne...@zen.khoral.com) wrote:
: 1) multiple `correct' solutions

: Where there is more than one solution, and no solution scores
: more, or is `better' than others.

A fine example of this is the medicine bottle in "Curses." There are at
least half a dozen ways to open it.

: 2) one optimal solution


: Where there is one correct solution, further refined by:
: a) alternative `wrong' solutions
: These are often solutions which seem right short term,
: but later on are revealed as red-herrings, for example.
: For example, getting through the Guarded Door in Enchanter.

I don't like to use these, simply because they necessitate saving and
restoring later. This was a problem I encountered at a couple of points
in "Path to Fortune." [SPOILERS...]

A couple of players suggested that, in blocking the bowman's shot, some of
the other items would work just as well as the piece of metal. The problem
was, you needed to use the metal, or you wouldn't be able to solve another
puzzle much later in the game. I didn't want players getting irked over
this, so I was forced to add special "nice try" responses for some of these
items.

Enchanter takes a slightly different method, with Belboz telling you in no
uncertain terms that perhaps there was a better way. This works all right
as well, but unfortunately Enchanter doesn't provide an undo command so the
player can correct the error. (Then again, he should have saved before
using such a powerful spell. But that's another thread.)

: b) alternative sub-optimal solutions


: Using such a solution does not preclude completion of the
: entire game say, but you won't get a 100% score.
: Wishbringer is an example.

These are much better than 2a. They let the player finish, which gives a
sense of satisfaction, but still let him/her know that there are better
ways. The alternate solutions are treated more like "amusing stuff" than
anything else.

--
C.E. Forman cef...@rs6000.cmp.ilstu.edu
Read the I-F e-zine XYZZYnews, at ftp.gmd.de:/if-archive/magazines/xyzzynews,
or on the Web at http://www.interport.net/~eileen!
* Interactive Fiction * Beavis and Butt-Head * The X-Files * MST3K * C/C++ *

Bill Lash

unread,
Jan 24, 1996, 3:00:00 AM1/24/96
to
In article <4e3tle$6...@lynx.unm.edu>, Neil Bowers <ne...@zen.khoral.com> wrote:
>Mark Borok (ma...@pcix.com) wrote:
>: I've always liked the idea of a game where there is
>: more than one solution to a given problem. Anyone know of games like this?
>
>This can be further refined into two categories:
>
> 1) multiple `correct' solutions
>
> Where there is more than one solution, and no solution scores
> more, or is `better' than others.
>
> I can't think of any large examples offhand, but there are quite
> a few of the form "how to persuade an NPC to do something for you".
>
Spoiler warning for Zork 1:



















In zork 1 the gold bar could be taken from the echo room by either
typing "echo" in which case the accoustics of the room were shattered,
or, you could open up the Dam and let the water drain from the
reservior, then close it. You then had several turns to take the gold
bar before the echo room returned to it's original state. I believe
that both gave you full credit.

> 2) one optimal solution
>
> Where there is one correct solution, further refined by:
>
> a) alternative `wrong' solutions
>
> These are often solutions which seem right short term,
> but later on are revealed as red-herrings, for example.
> For example, getting through the Guarded Door in Enchanter.
>

> a) alternative sub-optimal solutions


>
> Using such a solution does not preclude completion of the
> entire game say, but you won't get a 100% score.
> Wishbringer is an example.
>

>I think 2a is the most frequently used of these, but I don't have a huge
>experience to draw on.
>

>taxonomically,
>neilb


--
Bill Lash
la...@tellabs.com

--
Bill Lash
la...@tellabs.com

Neil Bowers

unread,
Jan 24, 1996, 3:00:00 AM1/24/96
to
Mark Borok (ma...@pcix.com) wrote:
: I've always liked the idea of a game where there is
: more than one solution to a given problem. Anyone know of games like this?

This can be further refined into two categories:

1) multiple `correct' solutions

Where there is more than one solution, and no solution scores
more, or is `better' than others.

I can't think of any large examples offhand, but there are quite
a few of the form "how to persuade an NPC to do something for you".

2) one optimal solution

Reply all
Reply to author
Forward
0 new messages