Increase PV LMR to SF 1.8 levels

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index f5e1a00002b2fc1fc21035d3835c710632132ca7..12481d4083bae3fc6d48cfb733938ec91acd595b 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -347,7 +347,7 @@ void init_search() {
   // Init reductions array
   for (hd = 1; hd < 64; hd++) for (mc = 1; mc < 64; mc++)
   {
-      double    pvRed = 0.33 + log(double(hd)) * log(double(mc)) / 4.5;
+      double    pvRed = log(double(hd)) * log(double(mc)) / 3.0;
       double nonPVRed = 0.33 + log(double(hd)) * log(double(mc)) / 2.25;
       ReductionMatrix[PV][hd][mc]    = (int8_t) (   pvRed >= 1.0 ? floor(   pvRed * int(ONE_PLY)) : 0);
       ReductionMatrix[NonPV][hd][mc] = (int8_t) (nonPVRed >= 1.0 ? floor(nonPVRed * int(ONE_PLY)) : 0);
@@ -1070,7 +1070,6 @@ namespace {
         && !isCheck
         &&  refinedValue < beta - razor_margin(depth)
         &&  ttMove == MOVE_NONE
-        &&  (ss-1)->currentMove != MOVE_NULL
         && !value_is_mate(beta)
         && !pos.has_pawn_on_7th(pos.side_to_move()))
     {
@@ -1287,6 +1286,17 @@ split_point_start: // At split points actual search starts from here
 
               continue;
           }
+
+          // Prune neg. see moves at low depths
+          if (   predictedDepth < 2 * ONE_PLY
+              && bestValue > value_mated_in(PLY_MAX)
+              && pos.see_sign(move) < 0)
+          {
+              if (SpNode)
+                  lock_grab(&(sp->lock));
+
+              continue;
+          }
       }
 
       // Step 13. Make the move