3.5.5: tune null move depth (#283)

vshcherbyna · web-flow · commit 9b93cfb3bcba · 2023-07-15T21:51:35.000+01:00
http://chess.grantnet.us/test/32793/ ELO | 6.00 +- 3.79 (95%) SPRT | 10.0+0.10s Threads=1 Hash=8MB LLR | 2.97 (-2.94, 2.94) [0.00, 3.00] GAMES | N: 16504 W: 4362 L: 4077 D: 8065 http://chess.grantnet.us/test/32794/ ELO | 2.60 +- 2.07 (95%) SPRT | 60.0+0.60s Threads=1 Hash=64MB LLR | 2.95 (-2.94, 2.94) [0.00, 3.00] GAMES | N: 52904 W: 13200 L: 12804 D: 26900 bench: 19300902
diff --git a/src/search.cpp b/src/search.cpp
@@ -291,7 +291,7 @@ EVAL Search::abSearch(EVAL alpha, EVAL beta, int depth, int ply, bool isNull, bo
         //   null move
         //
 
-        if (!isNull && depth >= 2 && bestScore >= beta && (!ttHit || !(hEntry.m_data.type == HASH_BETA) || ttScore >= beta) && m_position.NonPawnMaterial()) {
+        if (!isNull && depth >= 3 && bestScore >= beta && (!ttHit || !(hEntry.m_data.type == HASH_BETA) || ttScore >= beta) && m_position.NonPawnMaterial()) {
             int R = 5 + depth / 6 + std::min(3, (bestScore - beta) / 100);
 
             m_position.MakeNullMove();
diff --git a/src/uci.cpp b/src/uci.cpp
@@ -31,7 +31,7 @@
 #include <iostream>
 #include <sstream>
 
-const std::string VERSION = "3.5.4";
+const std::string VERSION = "3.5.5";
 const std::string ARCHITECTURE = " 64 "
 
 #if _BTYPE==0
