About FIBS rating
Lucifer
Piergiorgio Di Francesco <pi...@ifr15.luftfahrt.uni-stuttgart.de> wrote:
>Hallo,
>
>I'd like to know three things about rating on FIBS:
>
>1) if the points that you get or lose in each match depend on the length of the match (i.e.
>if you get more points in a 3 points match or in a 11 point match);
Yes (with a few rare exceptions), you will gain more rating pts. from
winning a longer match, and lose more rating pts. from losing a longer
match. In general, a match's "worth" varies on the order of the
square-root of the length of the match (i.e. a 20 pt. match is "worth"
twice as much as a 5 pt. match). (But see below if you are more interested.)
>2) if the points you get depend on the gap in the match between you and your opponent
>(i.e. if it is the same to win 11-0 or 11-10);
No. For example, winning an 11 pt. match by a score of 11-10 has the
same effect on your rating as winning by a score of 11-0 (or even 12-0, etc.)
>3) if the points you get depend on the rating of your opponent (i.e if you get more points
>against a better rating player than you, than against an opponent which is behind you in
>the rating list).
Yes, beating a strong player will earn you more rating pts. than beating
a weak player. Conversely, losing to a weak player will decrease your
rating more than losing to a strong player.
>Thanks
>
>Piergiorgio (piero)
>
>-- NewsGrazer, a NeXTstep(tm) news reader, posting --
[deleted]
--
Judging from your previous posts, you seem QUITE interested in the
backgammon scene/FIBS. The best advice that I can give newcomers to FIBS
is to spend approximately one hour reading the man files (type either 'man' or
'help'). Familiarizing yourself with commands you may not use for awhile
may seem like a waste of time, but becoming familiar with FIBS and its
commands from the very beginning will enable you to enjoy it better, no doubt.
For example, this is the process you might go through to find out more
about ratings:
> help
NAME
help - help on different topics
SYNOPSIS
help
help <topic>
DESCRIPTION
'help <topic>' displays the help available on <topic>
Help is currently available on the following topics:
about
accept autologin + away back beaver
beginner board boardstyle bye client +
[stuff deleted]
time timezones tinyfugue + toggle unwatch
version watch where whisper who
Topics marked with + are new. Topics marked with * have changed recently.
> help ratings
NAME
ratings - Display information from the rating list
SYNOPSIS
ratings [<name>|all] [from <number>] [to <number>]
DESCRIPTION
You'll see the first 20 entries of the current rating list if you just
type 'ratings'. You can see the ratings of all players that are currently
logged in with the who command. To see the ratings of a player called
<name> type 'ratings <name>'. To see the ratings of all active players
type 'ratings all'. Beware: This list can be very long.
The optional 'from <number>' and 'to <number>' arguments override the
default positions 'from 1 to 20' for the rating list output.
Every player starts with a rating of 1500 points and an experience of 0.
Every match you play (except unlimited matches) changes your rating. If
your experience is greater than 50 you'll appear in the rating list.
To see how rating changes are calculated type 'help formula'. To see a
brief calclation of the rating change after a match make sure that your
ratings toggle is set to YES.
ETHICS
There are several ways to manipulate the rating list and get a high rating.
This is cheating and not fair. Until there is a way to prevent cheating
the sysop will erase accounts that have been manipulated.
SEE ALSO
formula, names, toggle, toggle-ratings, who
> help formula
NAME
formula - The formulas used to calculate rating changes
DESCRIPTION
These are the formulas used to determine the ratings of a player:
Let's say that two players P1 and P2 were playing a n-point match.
The ratings of the players are r1 for P1 and r2 for P2 .
Let D = abs(r1-r2) (rating difference)
Let P_upset = 1/(10^(D*sqrt(n)/2000)+1) (probability that underdog wins)
Let P=1-P_upset if the underdog wins and P=P_upset if the favorite wins.
For the winner:
Let K = max ( 1 , -experience/100+5 )
The rating change is: 4*K*sqrt(n)*P
For the loser:
Let K = max ( 1 , -experience/100+5 )
The rating change is: -4*K*sqrt(n)*P
The 'experience' of a player is the sum of the lengths of all matches
a player has finished. Every player starts with a rating of 1500 and
an experience of 0.
SEE ALSO
ratings
--
So from the man (help) pages, we have obtained an exact formula for the
manner in which rating change is processed (amazing! :-))
You should be able to get more than enough information on every FIBS
command from 'help'. If you have any questions, ask/shout on FIBS that you
need help understanding something... Feel free to ask me (don't be scared
off by my birthname!) a question if I'm connected...
--
If you have read/skimmed this far, you should be able to see that you do,
in fact, gain more from beating a stronger opponent, etc.
(For those REALLY interested, determine the rating changes involved in 1
and 99 pt. matches for players with large rating differences; you may be
slightly surprised (Example: player A is rated 1800 with 400 experience,
player B is rated 1200 with 400 experience. In a 1 pt. match, A gets +1.34
pts. for winning and -2.66 pts. for losing. In a 99 pt. match, A gets
+0.04 pts. for winning, -39.76 pts. for losing (in both cases A and B's
losses/gains are opposite in nature). Thus A will gain more for winning a
1 pt. match, and B will lose less for losing a 99 pt. match. However, it
could be said that the "worth" of the 1 pt. match was on the order of 4
pts. and the "worth" of the 99 pt. match was on the order of
4 * {99 ^ (1/2)} =~ 39.80 pts. Figure out the details on your own if you
are interested.))
--Satan (on FIBS too)