Author: blass uri
Date: 13:21:55 05/24/00
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On May 24, 2000 at 15:34:08, 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. The fact that there are more draws in big depthes can be explained by the fact that part of the opening in chess lead to draw if the sides do not do stupid mistakes. In this case the difference between 5 plies and 6 plies may be important because the sides do stupid mistakes but when you search more than 10 plies you do not do stupid mistakes so 11 plies can draw against everything above 11 plies. I saw some cases in the ssdf games when the draw was clearly result of book because the sides had nothing better than to repeat moves after the opening. I believe that there are some cases that are less trivial when the opening is leading to a draw position that is not drawn by repetition but searching deeper cannot help to get more than a draw. Uri
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