From 13426a93c187c4953388a4484b8da69ee6f26fa3 Mon Sep 17 00:00:00 2001 From: Stefan Geschwentner Date: Thu, 23 Nov 2023 22:13:11 +0100 Subject: [PATCH] Simplify history update. Removal of the slowdown factor from the history update formula with corresponding adjustment of the stat bonus used in the search. Passed STC: https://tests.stockfishchess.org/tests/view/655e1079136acbc573544744 LLR: 2.93 (-2.94,2.94) <-1.75,0.25> Total: 128096 W: 32355 L: 32235 D: 63506 Ptnml(0-2): 466, 15187, 32573, 15405, 417 Passed LTC: https://tests.stockfishchess.org/tests/view/655f4e60136acbc573546266 LLR: 2.95 (-2.94,2.94) <-1.75,0.25> Total: 50652 W: 12653 L: 12459 D: 25540 Ptnml(0-2): 28, 5666, 13751, 5846, 35 closes https://github.com/official-stockfish/Stockfish/pull/4883 Bench: 1303857 --- src/movepick.h | 2 +- src/search.cpp | 6 +++--- 2 files changed, 4 insertions(+), 4 deletions(-) diff --git a/src/movepick.h b/src/movepick.h index 299925a5..e032b0c7 100644 --- a/src/movepick.h +++ b/src/movepick.h @@ -58,7 +58,7 @@ class StatsEntry { assert(abs(bonus) <= D); // Ensure range is [-D, D] static_assert(D <= std::numeric_limits::max(), "D overflows T"); - entry += (bonus * D - entry * abs(bonus)) / (D * 5 / 4); + entry += bonus - entry * abs(bonus) / D; assert(abs(entry) <= D); } diff --git a/src/search.cpp b/src/search.cpp index c878b0ab..55be43b3 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -94,10 +94,10 @@ constexpr int futility_move_count(bool improving, Depth depth) { } // History and stats update bonus, based on depth -int stat_bonus(Depth d) { return std::min(364 * d - 438, 1501); } +int stat_bonus(Depth d) { return std::min(291 * d - 350, 1200); } // History and stats update malus, based on depth -int stat_malus(Depth d) { return std::min(452 * d - 452, 1478); } +int stat_malus(Depth d) { return std::min(361 * d - 361, 1182); } // Add a small random component to draw evaluations to avoid 3-fold blindness Value value_draw(const Thread* thisThread) { @@ -746,7 +746,7 @@ Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth, boo // Use static evaluation difference to improve quiet move ordering (~4 Elo) if (is_ok((ss - 1)->currentMove) && !(ss - 1)->inCheck && !priorCapture) { - int bonus = std::clamp(-18 * int((ss - 1)->staticEval + ss->staticEval), -1812, 1812); + int bonus = std::clamp(-14 * int((ss - 1)->staticEval + ss->staticEval), -1449, 1449); thisThread->mainHistory[~us][from_to((ss - 1)->currentMove)] << bonus; if (type_of(pos.piece_on(prevSq)) != PAWN && type_of((ss - 1)->currentMove) != PROMOTION) thisThread->pawnHistory[pawn_structure(pos)][pos.piece_on(prevSq)][prevSq] << bonus / 4; -- 2.39.2