Prune all negative see moves at low depths
authorJoona Kiiski <joona.kiiski@gmail.com>
Tue, 30 Nov 2010 12:46:41 +0000 (14:46 +0200)
committerMarco Costalba <mcostalba@gmail.com>
Thu, 2 Dec 2010 06:42:18 +0000 (07:42 +0100)
After 2036 games Mod- Orig:
381 - 278 - 1377 ELO +17 (+- 6.2) LOS 99%

One of the biggest increases ever !

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
src/search.cpp

index f5e1a00002b2fc1fc21035d3835c710632132ca7..f7718ce442d50136b9508405bc6f3bdb76e34654 100644 (file)
@@ -1287,6 +1287,17 @@ split_point_start: // At split points actual search starts from here
 
               continue;
           }
 
               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
       }
 
       // Step 13. Make the move