Backgame problem
Marty Storer
X inner board
+ -- -- -- -- -- -- +++++ -- -- -- -- -- -- +
| X X X X X | | X X X O O |
| X X X | | X X X O O |
| | | O |
| | | |
| | | |
| | | | +---+
| | | | | 1 |
| | | | +---+
| | | |
| | | |
| O O | | |
| O O | | O O |
| O O | | O O X |
+ -- -- -- -- -- -- +++++ -- -- -- -- -- -- +
O to play 43
Marc Ringuette
Best: 8-5,7-3 (move past)
2nd: 8-4,7-4 (point on him)
3rd: 7-4,7-3 (make blots)
Our timing is bad, but blotting doesn't help it much since we quickly enter.
Pointing on X gives us a small chance of keeping the last checker back, but
otherwise slows him down and lets him off the hook on the 9 rolls where he
dances, which otherwise would be bad for him. So just move past and hope
he rolls faster than you do.
John Robert Klein
I think you're right Mark and I was wrong in my earlier reply to this
problem where I said to leave lots of blts to preserve Xs timing.
O's timing isn't soooo bad so (s)he may be able to keep much of hir board
(i'm trying "gender neutral" pronouns :) until s/he can escape the back
checkers. O may even be able to win the game this way and is likely to
at least avoid the gammon. So, I agree 100% with your rankings. Good
analysis.
JK
Elliott C Winslow
|. O O X X X | | X X X . X X|
| O O X X X | | X X X |
| O | | |
| | | |
| | | |
| | | O O |
|. . . X O O | | O O . . . .|
|1 2 3 4 5 6 | | 7 8 9 10 11 12|
O to play 43
John Klein's latest comment:
> Obviously 8/4*, 7/4 is wrong.
> I see 2 reasonable plays: 7/4*, 7/3 or 8/4*, 6/3. Both plays
> are made in the hope that X will have to hit 2 men and that O will
> stay on the bar for a few rolls and not have to destroy his board.
> O's position is pretty precarious since X has lots of ground to cover
> before he has to break his board but with a little luck O will keep
> most of his board intact until he can escape a checker.
First off, X has accomplished a six-prime, with quite a few pips of
timing, so it looks *very* bad for O. It might just be right to not
get any more men sent back, to minimize the gammon. Oh, shame on me
for thinking this way!
Second, 8-4x 7-4 might not be so bad, since if he comes in on the 1,
he might actually lose the timing battle. It wouldn't even take a
miracle, since the men on the 8 point are some time. Even if he
enters on the 2, there's some hope that he'll have some problems.
If 8-5, 7-3, can he *really* crack on 4-4!? Almost a reason to play
it.
With the 6-prime, I think that the suicide plays are just that.
--Elliott
Elliott C Winslow
my keyboard...
Dick King
8/4*/1.
The slim reed you're grasping is
* getting hit on the ace point, dancing while X gets bogged down
or
* burning bigtime bit only with the checkers NOT primed.
Reed 2 is a bit plumper. I would not argue with a chouette player who wanted
to play 8/4* 5/2.
Before PC my circle used to call this sort of thing a "Polish prime".
A full Polish prime would be six consecutive blots.
-dk
Marty Storer
(My rankings would be the same as Marc's except with the second and third
reversed. See below...)
This is another previously published problem: #97 from Barclay Cooke's
_Paradoxes_and_Probabilities_.
It is a somewhat silly problem because the cube is in the middle. It would
be more interesting if O owned the cube. Here, most of the time X ends up
winning by doubling O out, as he can (but shouldn't) do right away.
Cooke sees two alternatives, making the 4 point, and leaving blots with
7/3, 7/4* to try to adjust timing. Nowhere does he mention the cube;
it doesn't figure into his analysis. He rejects making the 4 point in
favor of trying to improve timing by being hit.
Here's how I analyze this position: O's timing is rotten, so X is playing
for gammon. How should O (1) play to avoid the gammon, (2) play to win
the game?
Playing to win is dangerous, because the best tries to win are those that
get more men sent back. X can double O out if things start to look
dangerous, and even when X regains his market it's very seldom by much.
Meanwhile, the more men sent back, the more likely X is to win a gammon.
Do blotting plays make a gammon less likely for X because they force X
to take more double-outs? I don't think so, but as usual I haven't
rolled this out.
Playing to avoid the gammon *by refusing to leave more blots* is also
dangerous, because O moves forward faster, thus decreasing winning
chances and allowing X to play for gammon longer.
I don't know the answer, but I'd play 8/5, 7/3. This at least lets X
play all of his big numbers and even gives him one number to break his
prime (44). I'm more afraid of the variations where X sends another
man or two back and O cracks his board anyway, than I am of the variations
where O cracks his board but remains with only five men back.
How about if O owns the cube?
Then I think I'd play 7/3, 7/4*. O is in it to the end; I think leaving
the blots increases her chances to win, and doesn't increase her chance of
getting gammoned by twice as much as it increases her winning chances
(assuming a money game). Just instinct (in-stink?) talking.
There's another blotting play that I think someone mentioned: 8/4*, 6/3,
activating X's 66 and 65, which doesn't happen after 7/3, 7/4*. I
wouldn't make that play whether I owned the cube or not--it wrecks the
board possibly beyond repair, and makes it more likely that X can send
some men back and still leave O with a cheesy and hard-to-improve board
or a busted one.
Play well,
Marty
PS Walter Trice claims to have the Master Error List for _P_and_P_.
I'll ask what the line is on this one.
Rob Chauncey
"time", "timing", "checker", and "dancing"?
Sorry, but I love backgammon, and want to be able to keep up with you
all...
I would have gone 8-5, 6-3 on this one, figuring on having the rolls
on the bar to wreck X's board.
Rob Chauncey
rcha...@occs.cs.oberlin.edu
Marty Storer
> Could someone please explain to a novice player the terms
> "time", "timing", "checker", and "dancing"?
Time: number of average rolls (8 1/6 pips = 1 average roll) or number of
pips. Ex. "How much time do we have before we bust?"
--"About 3 rolls. [About 25 pips.]"
Timing: "The position viewed in terms of the general future development
of the game." --Paul Magriel, _Backgammon_, p. 402.
Amount of "playability" in a position, especially as compared
to that in your opponent's position; number of average rolls
or pips that can probably be played without having to make a
major concession (like leaving a blot or breaking a key point).
Checker: A man; a piece; one of the round things you move.
Dancing: Staying on the bar. E.g. _How_Can_I_Keep_From_Dancing?_ by
Danny Kleinman.
>
> Sorry, but I love backgammon, and want to be able to keep up with you
> all...
> I would have gone 8-5, 6-3 on this one, figuring on having the rolls
> on the bar to wreck X's board.
You mean 8-4*, 6-3 (or 8/4*, 6/3)--asterisk indicates a hit.
Play well,
Marty
Hol3ly
> Could someone please explain to a novice player the terms
> "time", "timing", "checker", and "dancing"?
>
> Sorry, but I love backgammon, and want to be able to keep up with you
> all...
I know Marty's already answered this one, but I thought I'd also throw
in that "fanning" is synonymous with "dancing", just in case you didn't
know that one. (And I hope I spelled synonymous correctly... no dictionary
handy!)
Maybe we should compile a list of common terms for newbees? I can put
it in the BKGAMMON archives on indycms.iupui.edu where people can
request to have it sent to them... it might also be helpful to have
some common notation explanations there as well. Anonymous ftp would
be nice, but we can't set that up here...
----
Holly Stowe (st...@indycms.iupui.edu or hst...@indycms.iupui.edu)
Zen computer poetry We're not stupid... just consider
If an error is unexpected us to be technologically impaired.
How can it have a number? -Lewis Grizzard
Hol3ly
>
> Checker: A man; a piece; one of the round things you move.
So much for genderless backgammon... *grin*
Funny... but most of the men I know consider "man" and "piece" to be
opposites. ;-)
(A little weak humor... but then... it's Monday. Gee, maybe that means
it's really "week" humor. :-)
Larry Hunter
Holly Stowe writes:
I can put it in the BKGAMMON archives on indycms.iupui.edu where
people can request to have it sent to them...
That sounds interesting -- I'd never seen mention of the BKGAMMON
archives before. What's in it, and how does one use it?
Larry
--
Lawrence Hunter, PhD.
National Library of Medicine
Bldg. 38A, MS-54
Bethesda. MD 20894
(301) 496-9300
(301) 496-0673 (fax)
hun...@nlm.nih.gov (internet)
Marty Storer
" In article <MARTYS.92A...@escalus.juliet.ll.mit.edu>, mar...@juliet.ll.mit.edu ( Marty Storer ) writes:
: >
: > Checker: A man; a piece; one of the round things you move.
: ^^^ ^^^^^
: So much for genderless backgammon... *grin*
:
: Funny... but most of the men I know consider "man" and "piece" to be
: opposites. ;-)
I could tell some stories about the "screw you" and "screw me" bearoff
formations...
But a sexist backgammon limerick will have to suffice. This appeared
in the _Chicago_Point_ in 1985 (?):
A brazen young wench, Antoinette,
Invaded an all-male chouette.
She stripped to her socks
And cried, "Who wants the box?"
They haven't stopped arguing yet!
--MS
No allusion to Antoinette Williams intended (I don't think).
--Marty
Holly Lee Stowe
>Holly Stowe writes:
>
> I can put it in the BKGAMMON archives on indycms.iupui.edu where
> people can request to have it sent to them...
>
>That sounds interesting -- I'd never seen mention of the BKGAMMON
>archives before. What's in it, and how does one use it?
I have rec.games.backgammon gated to Bitnet through a Listserv list
called BKGAMMON so messages from each go to the other. In addition,
all the messages that come through BKGAMMON (therefore, rec.games.backgammon)
get logged into notebooks that are kept on a monthly basis. (The notebooks
are only available those subscribed to the BKGAMMON list by direct request,
but I can send them to anyone who wants them, and someday when I get my
act together and caught up, I will try to make them available to the
general public by request.) But, if someone has a need, I can put files
out there as well (with a little cooperation from the local Powers That Be)
that can be requested by the general public via a mail request to
list...@indycms.iupui.edu.
To subscribe to BKGAMMON (which will send mail rather than having to use
rn or the like) you can send mail to list...@indycms.iupui.edu with the
command: SUBscribe BKGAMMON Firstname Lastname
If anyone has any other questions, send them to me at hst...@indycms.iupui.edu
and I'll do what I can to answer them.
-Holly-
Rob Chauncey
> So much for genderless backgammon... *grin*
>
> Funny... but most of the men I know consider "man" and "piece" to be
> opposites. ;-)
Wow. That is *really* bad in more than one way...
--
-----------------------------------------------------------------------------
Rob Chauncey | Vote Perot.
rcha...@occs.cs.oberlin.edu |
rcha...@ultrix.ramapo.edu | Finally, a viable candidate.
SDC...@OBERLIN.BITNET |
-----------------------------------------------------------------------------
John Robert Klein
I see 2 reasonable plays : 7/4*, 7/3 or 8/4*, 6/3. Both plays
are made in the hope that X will have to hit 2 men and that O will
stay on the bar for a few rolls and not have to destroy his board.
O's position is pretty precarious since X has lots of ground to cover before
he has to break his board but with a little luck O will keep most of his
board intact until he can escape a checker.
jk