From da937e219ee7981966ac29fc11c43470a505ff18 Mon Sep 17 00:00:00 2001 From: Joost VandeVondele Date: Wed, 5 Oct 2022 22:59:05 +0200 Subject: [PATCH] Revert "Mix alpha and statScore for reduction" This reverts commit 8bab09749dd00951bfa9c5f89f6e35bded76c8a9. In this form the patch reduces mate finding effectiveness, as the large alpha value has negative influence on the reductions. see also https://github.com/official-stockfish/Stockfish/pull/4183 Bench: 4114228 --- src/search.cpp | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/src/search.cpp b/src/search.cpp index 46463b32..4b6b497a 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -787,9 +787,9 @@ namespace { // The depth condition is important for mate finding. if ( !ss->ttPv && depth < 8 - && eval - futility_margin(depth, improving) - (ss-1)->statScore / 301 >= beta + && eval - futility_margin(depth, improving) - (ss-1)->statScore / 303 >= beta && eval >= beta - && eval < 28692) // larger than VALUE_KNOWN_WIN, but smaller than TB wins + && eval < 28031) // larger than VALUE_KNOWN_WIN, but smaller than TB wins return eval; // Step 9. Null move search with verification search (~22 Elo) @@ -1179,7 +1179,7 @@ moves_loop: // When in check, search starts here - 4433; // Decrease/increase reduction for moves with a good/bad history (~30 Elo) - r -= (ss->statScore + 5 * alpha) / 15448; + r -= ss->statScore / 13628; // In general we want to cap the LMR depth search at newDepth, but when // reduction is negative, we allow this move a limited search extension