Author: Adam Oellermann
Date: 09:46:29 09/05/01
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On September 05, 2001 at 12:15:37, Uri Blass wrote: >On September 05, 2001 at 07:53:50, guy haworth wrote: > >> >>In the Ken-Thompson-themed ICGA Journal (June, 2001), Ernst Heinz published his >>latest self-play experiment results. >> >>Engines with different guaranteed-depth(?)-parameters were pitted against each >>other. >> >>The matches of the experimetn (3,000 games each) suggest that: >> >> 12-ply was 84 ELO points better than 11 ply >> 11-ply was 92 ELO points better than 10 ply >> 10-ply was 115 ELO points better than 9 ply >> >>Fairly strong indications of decreasing returns from increasing search. No >>doubt a proper statistical analysis will follow. >> >> >>An extra ply seems to require 4-6 times the 'effective power', so a factor of 36 >>- if realised across the system - is only 2 plies. > >I know that the top programs of today have usually branching factor that is >close to 3 and not 4-6 so a factor of 36 is more than 3 plies. Ernst Heinz probably used Dark Thought for this research - while perhaps not a top program these days, I reckon it's branching factor must be comparable to the top programs. The article didn't say that the branching factor was 3, but that the "effective power" (I'm guessing CPU time and memory utilisation are factors in "effective power"), determined empirically, required for an extra ply is 4 - 6. > >I also know that based on the ssdf results 70 elo per doubling the speed makes >more sense. > >70 elo per doubling means something like 110 elo per ply. >84 elo per ply when going from 11 plies to 12 plies seems to be wrong because >the programs in the ssdf games get deeper than 12 plies. He's not saying 84 elo per ply; he's saying that once you hit 11 ply, the next ply will buy you around 84 elo. >Uri I think discounting the results published by Ernst Heinz because of the SSDF's figures is dangerous. The SSDF, after all, is an experiment to test relative performance of different chess engines. Ernst Heinz's experiment is clearly designed to determine the performance improvements obtained by increased search depth, and in this domain his data are probably more accurate than SSDF figures. - Adam
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