From 7b064752943b67eaa7ef93f1109acfad50b4ecc2 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Ste=CC=81phane=20Nicolet?= Date: Sun, 15 Sep 2019 23:18:54 +0200 Subject: [PATCH] Scale down endgame factor when shuffling This patch decreases the endgame scale factor using the 50 moves counter. Looking at some games with this patch, it seems to have two effects on the playing style: 1) when no progress can be made in late endgames (for instance in fortresses or opposite bishops endgames) the evaluation will be largely tamed down towards a draw value. 2) more interestingly, there is also a small effect in the midgame play because Stockfish will panic a little bit if there are more than four consecutive shuffling moves with an advantage: the engine will try to move a pawn or to exchange a piece to keep the advantage, so the follow-ups of the position will be discovered earlier by the alpha-beta search. passed STC: LLR: 2.95 (-2.94,2.94) [0.50,4.50] Total: 23017 W: 5080 L: 4805 D: 13132 http://tests.stockfishchess.org/tests/view/5d7e4aef0ebc59069c36fc74 passed LTC: LLR: 2.95 (-2.94,2.94) [0.00,3.50] Total: 30746 W: 5171 L: 4911 D: 20664 http://tests.stockfishchess.org/tests/view/5d7e513d0ebc59069c36ff26 Pull request: https://github.com/official-stockfish/Stockfish/pull/2304 Bench: 4272173 --- src/evaluate.cpp | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/src/evaluate.cpp b/src/evaluate.cpp index d92239c1..a7a091ab 100644 --- a/src/evaluate.cpp +++ b/src/evaluate.cpp @@ -769,8 +769,9 @@ namespace { && pos.non_pawn_material() == 2 * BishopValueMg) sf = 16 + 4 * pe->passed_count(); else - sf = std::min(40 + (pos.opposite_bishops() ? 2 : 7) * pos.count(strongSide), sf); + sf = std::min(sf, 36 + (pos.opposite_bishops() ? 2 : 7) * pos.count(strongSide)); + sf = std::max(0, sf - (pos.rule50_count() - 12) / 4 ); } return ScaleFactor(sf); -- 2.39.2