Use increased LMR horizont also in PV search

Tord says that using a lower horizon at PV nodes
looks strange and inconsistent with the general
philosophy of our search (i.e. always being more
conservative at PV nodes). So set LMR at 3 also
on search_pv().

Test result after 601 games seems to confirm this.

Mod vs Orig +156 =318 -127 52.41%  315.0/601  +17 ELO

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

diff --git a/src/search.cpp b/src/search.cpp
index b4e9b14c6c5073c540cb33fc5657c80991a96ba2..de343144b4c02efac3fe56c482c6f3bb244c7fea 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -1080,7 +1080,7 @@ namespace {
       {
         // Try to reduce non-pv search depth by one ply if move seems not problematic,
         // if the move fails high will be re-searched at full depth.
       {
         // Try to reduce non-pv search depth by one ply if move seems not problematic,
         // if the move fails high will be re-searched at full depth.

-        if (    depth >= 2*OnePly
+        if (    depth >= 3*OnePly

             &&  moveCount >= LMRPVMoves
             && !dangerous
             && !moveIsCapture
             &&  moveCount >= LMRPVMoves
             && !dangerous
             && !moveIsCapture