Futility pruning till ply 6 included

Seems good:

After 796 games: +211 = 393 -192 +8 elo

Signed-off-by: Marco Costalba <mcostalba@gmail.com>

diff --git a/src/search.cpp b/src/search.cpp
index a4ce7eff3abf10c7a76c057c75271a4f1a4949df..768a22a4d36b50ce919248e7c0dc4cc95fe286c8 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -1314,12 +1314,14 @@ namespace {
               continue;
 
           // Value based pruning
               continue;
 
           // Value based pruning

-          if (depth < 6 * OnePly && approximateEval < beta)
+          if (depth < 7 * OnePly && approximateEval < beta)

           {
               if (futilityValue == VALUE_NONE)
                   futilityValue =  evaluate(pos, ei, threadID)
           {
               if (futilityValue == VALUE_NONE)
                   futilityValue =  evaluate(pos, ei, threadID)

-                                + (depth < 2 * OnePly ? FutilityMargin1
-                                                      : FutilityMargin2 + (depth - 2*OnePly) * 32);
+                                + (depth < 2 * OnePly ? FutilityMargin1 :
+                                + (depth < 6 * OnePly ? FutilityMargin2 + (depth - 2*OnePly) * 32
+                                                      : FutilityMargin2 + (depth - 2*OnePly) * 64));
+

               if (futilityValue < beta)
               {
                   if (futilityValue > bestValue)
               if (futilityValue < beta)
               {
                   if (futilityValue > bestValue)