Simplify HinderPassedPawn bonus

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index e1ca7964922610a7691d9b56543e243ce82d0830..997cfd3b6a32c20ecbbb493dbb1e1cba8f87f536 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -71,16 +71,6 @@ namespace {
     return Value((175 - 50 * improving) * d / ONE_PLY);
   }
 
-  // Margin for pruning capturing moves: almost linear in depth
-  constexpr int CapturePruneMargin[] = { 0,
-                                         1 * PawnValueEg * 1055 / 1000,
-                                         2 * PawnValueEg * 1042 / 1000,
-                                         3 * PawnValueEg * 963  / 1000,
-                                         4 * PawnValueEg * 1038 / 1000,
-                                         5 * PawnValueEg * 950  / 1000,
-                                         6 * PawnValueEg * 930  / 1000
-                                       };
-
   // Futility and reductions lookup tables, initialized at startup
   int FutilityMoveCounts[2][16]; // [improving][depth]
   int Reductions[2][2][64][64];  // [pv][improving][depth][moveNumber]
@@ -957,13 +947,11 @@ moves_loop: // When in check, search starts from here
                   continue;
 
               // Prune moves with negative SEE (~10 Elo)
-              if (   lmrDepth < 8
-                  && !pos.see_ge(move, Value(-35 * lmrDepth * lmrDepth)))
+              if (!pos.see_ge(move, Value(-29 * lmrDepth * lmrDepth)))
                   continue;
           }
-          else if (    depth < 7 * ONE_PLY // (~20 Elo)
-                   && !extension
-                   && !pos.see_ge(move, -Value(CapturePruneMargin[depth / ONE_PLY])))
+          else if (   !extension // (~20 Elo)
+                   && !pos.see_ge(move, -PawnValueEg * (depth / ONE_PLY)))
                   continue;
       }