Further push singular extension

Extend for an extra half-ply in case the node is (probably) going to fail high. In this case the added overhead is limited. A novelity is the way this patch has been tested: Always in self-play but with a much longer TC to allow the singular extension to fully kick in and also (my impression) to have less noisy results. Ater 1015 games on my QUAD at 60"+0.05 Mod vs Orig 173 - 150 - 692 ELO +8
mcostalba · Oct 2, 2012 · 4c91dbc · 4c91dbc
1 parent 1b6b711
commit 4c91dbc
Showing 1 changed file with 1 addition and 1 deletion.
diff --git a/src/search.cpp b/src/search.cpp
@@ -863,7 +863,7 @@ namespace {
           ss->excludedMove = MOVE_NONE;
 
           if (value < rBeta)
-              ext = ONE_PLY;
+              ext = rBeta >= beta ? ONE_PLY + ONE_PLY / 2 : ONE_PLY;
       }
 
       // Update current move (this must be done after singular extension search)