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Subject: Re: A New Self-Play Experiment -- Diminishing Returns Shown with 95% Conf.

Author: Ed Schröder

Date: 21:27:03 05/24/00

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On May 24, 2000 at 20:02:23, Peter McKenzie wrote:

>Sounds like great work Ernst, I look forward to reading it.
>
>I've always wonder though if fixed depth games were the right way to go about
>looking for dimishing returns.  To me, it seems more useful to use fixed node
>counts (eg. 1 program is allowed N million nodes per move, vs same program being
>allowed M*N million nodes per move).  This would model more closely what happens
>when we get faster hardware.
>
>The problem with fixed depth is that the endgame is played at a much worse level
>than the rest of the game.  Well, worse in relation to what a chess program
>playing under a normal time control would do.  I mean, normally programs search
>much deeper in the endgame.

Matches 5 vs 6 ply make (some) sense in the mid-game. In the end-game
even matches 8 vs 9 ply are russian roulette. We don't know how many
games were decided in the end-game. I think the idea of Ernst is just
great but why not test 5/all vs 10/all, 10/all vs 20/all etc. IMO
results then are much more reliable to proof the truth behind dimishing
returns for chess programs.

Ed


>Perhaps my concern is irrelevant, I'd like to hear your opinion.
>
>Sorry if you have addressed this issue already, i'm unable to read your article
>right now.
>
>cheers,
>Peter
>
>On May 24, 2000 at 15:08:15, Ernst A. Heinz wrote:
>
>>Dear Fellow Computer-Chess Enthusiasts,
>>
>>In view of the current discussion about diminishing returns in the thread
>>"Ply Depth in Relation to ELO again", I like to share the results of my
>>latest self-play experiment with you.
>>
>>The stunning outcome of the new experiment is that it shows the existence
>>of diminishing returns for additional search in computer chess self-play
>>with 95% statistical confidence, exemplified by the program "Fritz 6"!
>>
>>The title and abstract of my M.I.T. LCS Technical Report on the
>>experiment follow below.
>>
>>***********************************************************************
>>
>>        ``A New Self-Play Experiment in Computer Chess''
>>
>>                         ABSTRACT
>>
>>This paper presents the results of a new self-play experiment in
>>computer chess. It is the first such experiment ever to feature search
>>depths beyond 9 plies and thousands of games for every single match.
>>Overall, we executed 17,150 self-play games (1,050--3,000 per match)
>>in one "calibration" match and seven "depth X+1 <=> X" handicap
>>matches at fixed iteration depths ranging from 5--12 plies. For
>>the experiment to be realistic and independently repeatable, we relied
>>on a state-of-the-art commercial contestant: "Fritz6", one of the
>>strongest modern chess programs available. The main result of our new
>>experiment is that it shows the existence of diminishing returns for
>>additional search in computer chess self-play with 95% statistical
>>confidence, exemplified by the program "Fritz6". The diminishing
>>returns manifest themselves by declining rates of won games and
>>reversely increasing rates of drawn games for the deeper searching
>>program versions. The rate of lost games, however, remains quite
>>steady for the whole depth range of 5--12 plies.
>>
>>***********************************************************************
>>
>>Please find the full report in gzip'ed PostScript format at the URL
>><http://supertech.lcs.mit.edu/~heinz/ps/new_exp.ps.gz>.
>>
>>Any comments welcome!
>>
>>=Ernst=
>>
>>P.S.
>>
>>Electronic preprints of my earlier publications on the relationship
>>between computing power and playing strength of chess programs are
>>available from http://supertech.lcs.mit.edu/~heinz/ and the WWW
>>pages of "DarkThought" at http://supertech.lcs.mit.edu/~heinz/dt/.



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