From 8e8234593190804babd36b8a8862e2bb1fc65bb7 Mon Sep 17 00:00:00 2001 From: Michael Chaly Date: Thu, 9 Dec 2021 19:33:06 +0300 Subject: [PATCH] Adjust singular extension depth restriction This patch is a modification of original idea by lonfom169 which had a good yellow run - do singular extension search with depth threshold 6 unless this is a PvNode with is a part of a PV line - for them set threshold to 8 instead. Passed STC https://tests.stockfishchess.org/tests/view/61b1080406b4c2dcb1b1128c LLR: 2.95 (-2.94,2.94) <0.00,2.50> Total: 84352 W: 21917 L: 21555 D: 40880 Ptnml(0-2): 288, 9524, 22185, 9896, 283 Passed LTC https://tests.stockfishchess.org/tests/view/61b1860a06b4c2dcb1b134a1 LLR: 2.95 (-2.94,2.94) <0.50,3.00> Total: 63520 W: 16575 L: 16237 D: 30708 Ptnml(0-2): 27, 6519, 18350, 6817, 47 https://github.com/official-stockfish/Stockfish/pull/3840 bench 4729473 --- src/search.cpp | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/src/search.cpp b/src/search.cpp index f3a96ae2..cded8614 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -1089,7 +1089,7 @@ moves_loop: // When in check, search starts here // a reduced search on all the other moves but the ttMove and if the // result is lower than ttValue minus a margin, then we will extend the ttMove. if ( !rootNode - && depth >= 7 + && depth >= 6 + 2 * (PvNode && tte->is_pv()) && move == ttMove && !excludedMove // Avoid recursive singular search /* && ttValue != VALUE_NONE Already implicit in the next condition */ -- 2.39.2