A try to implement Alexander Shashin's theory on a Stockfish's derived chess engine
Deeply revised Shashin theory Stockfish patch Remove optimism multiplier in nnue eval calculation The same formula had passed SPRT against an earlier version of master.
ShashChess 32 Added book management section (thanks to Khalid Omar PolyFish: see the Readme) Restored Minimum thinking time uci option Stockfish patch May 7,2023: Refine deeper post-lmr searches This patch improves logic conditions for performing deeper searches after passed LMR.
Instead of exceeding alpha by some margin now it requires to exceed the current best value - which may be lower than alpha (but never bigger since we update alpha with bestvalue if it exceeds alpha).
Stockfish patch Simplify stats assignment for Pv nodes This version is a release to demonstrate the superiority of ShashChess vs Stockfish thanks to
Again refined Shashin theory Updated and very refined testsuite Stockfish patch Apr 7, 2023 Depth Tweak and tuning tunes reduction related parameters, and introduces more reduction on found good moves.
credit for this patch goes also to candirufish Yoshie2000 dubslow peregrineshahin Vizvezdenec
ShashChess 31 Speedup and simplification in shashin theory Stockfish patch Assign negative stat bonuses for quiet moves at Pv nodes This patch assigns negative stat bonuses for quiet moves at pv nodes which are searched at depth greater than this node assumes, so are extended.
Solved a bug in winProbability implementation (replaced the map with an array). Improvements in Shashin theory. New net from stockfish testing framework, slightly better than the original one. Stockfish patch: Remove 'si' StateInfo variable/parameter. Since st is a member of position we don't need to pass it separately as parameter.
While being there also remove some line in pos_is_ok, where a copy of StateInfo was made by using default copy constructor and then verified it's correctedness by doing a memcmp. There is no point in doing that.
Speed up kns
ShashChess 29 Greatly improved Shashin theory: introduced winProbability concept: Shashin position's classification now is not only based on the score, but also on the depth/ply. Aligned with Stockfish patch 02/27/23 Update default net to nn-52471d67216a.nnue
Improved Shashin theory Stockfish patch Remove maxNextDepth This patch allows full PV search to have double extensions as well when extension == 1 && doDeeperSearch && doEvenDeeperSearch && !doShallowerSearch is true, which is extremely rare to occur.
ShashChess 27.2 No GoldDigger Update default net to nn-1e7ca356472e.nnue