singular margin and pvHit

Bench: 3691873
snicolet · Jan 10, 2019 · 9bd5e05 · 9bd5e05
1 parent 40171fb
commit 9bd5e05
Showing 1 changed file with 6 additions and 3 deletions.
diff --git a/src/search.cpp b/src/search.cpp
@@ -949,7 +949,8 @@ namespace {
           &&  tte->depth() >= depth - 3 * ONE_PLY
           &&  pos.legal(move))
       {
-          Value singularBeta = std::max(ttValue - 2 * depth / ONE_PLY, -VALUE_MATE);
+          Value singularBeta = std::max(ttValue - 2 * depth / ONE_PLY - 10 * pvHit, -VALUE_MATE);
+
           ss->excludedMove = move;
           value = search<NonPV>(pos, ss, singularBeta - 1, singularBeta, depth / 2, cutNode);
           ss->excludedMove = MOVE_NONE;
@@ -965,7 +966,9 @@ namespace {
           else if (cutNode && singularBeta > beta)
               return beta;
       }
-      else if (    givesCheck // Check extension (~2 Elo)
+
+      // Extension for checks (~2 Elo)
+      else if (    givesCheck
                &&  pos.see_ge(move))
           extension = ONE_PLY;
 
@@ -1043,7 +1046,7 @@ namespace {
 
           // Decrease reduction if position is or has been on the PV
           if (pvHit)
-              r -= 2 * ONE_PLY;
+              r -= ONE_PLY;
 
           // Decrease reduction if opponent's move count is high (~10 Elo)
           if ((ss-1)->moveCount > 15)