Tweak formula for pruning moves losing material

Simplify the "Prune moves with negative SEE" formula, by removing one multiplication and subtraction operation.
official-pikafish · Aug 7, 2023 · dcbbad6 · dcbbad6
1 parent 0779f7c
commit dcbbad6
Showing 1 changed file with 2 additions and 2 deletions.
diff --git a/src/search.cpp b/src/search.cpp
@@ -908,8 +908,8 @@ namespace {
 
               lmrDepth = std::max(lmrDepth, 0);
 
-              // Prune moves with negative SEE (~3 Elo)
-              if (!pos.see_ge(move, Value(-29 * lmrDepth * lmrDepth - 24 * lmrDepth)))
+              // Prune moves with negative SEE (~4 Elo)
+              if (!pos.see_ge(move, Value(-31 * lmrDepth * lmrDepth)))
                   continue;
           }
       }