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Stéphane Nicolet
be382bb0cf
* A better contempt implementation for Stockfish The round 2 of TCEC season 10 demonstrated the benefit of having a nice contempt implementation: it gives the strongest programs in the tournament the ability to slow down the game when they feel the position is slightly worse, prefering to stay in a complicated (even if slightly risky) middle game rather than simplifying by force into a drawn endgame. The current contempt implementation of Stockfish is inadequate, and this patch is an attempt to provide a better one. Passed STC non-regression test against master: LLR: 2.95 (-2.94,2.94) [-3.00,1.00] Total: 83360 W: 15089 L: 15075 D: 53196 http://tests.stockfishchess.org/tests/view/5a1bf2de0ebc590ccbb8b370 This contempt implementation is showing promising results in certains situations. For instance, it obtained a nice +30 Elo gain when playing with contempt=40 against Stockfish 7, compared to current master: • master against SF 7 (20000 games at LTC): +121.2 Elo • this patch with contempt=40 (20000 games at LTC): +154.11 Elo This was the result of real cooperative work from the Stockfish team, with key ideas coming from Stefan Geschwentner (locutus2) and Chris Cain (ceebo) while most of the community helped with feedback and computer time. In this commit the bench is unchanged by default, but you can test at home with the new contempt in the UCI options. The style of play will change a lot when using contempt different of zero (I repeat: not done in this version by default, however)! The Stockfish team is still deliberating over the best default contempt value in self-play and the best contempt modeling strategy, to help users choosing a contempt value when playing against much weaker programs. These informations will be given in future commits when available :-) Bench: 5051254 * Remove the prefetch No functional change.
42 lines
1.2 KiB
C++
42 lines
1.2 KiB
C++
/*
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Stockfish, a UCI chess playing engine derived from Glaurung 2.1
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Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
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Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
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Copyright (C) 2015-2017 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
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Stockfish is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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Stockfish is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef EVALUATE_H_INCLUDED
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#define EVALUATE_H_INCLUDED
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#include <string>
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#include "types.h"
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class Position;
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namespace Eval {
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const Value Tempo = Value(20); // Must be visible to search
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extern Score Contempt;
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std::string trace(const Position& pos);
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Value evaluate(const Position& pos);
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}
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#endif // #ifndef EVALUATE_H_INCLUDED
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