Disable null move pruning for horde chess

horde STC
LLR: 2.97 (-2.94,2.94) [0.00,10.00]
Total: 2289 W: 1212 L: 1076 D: 1
http://35.161.250.236:6543/tests/view/5c249b6d6e23db2472895633

horde LTC
LLR: 2.96 (-2.94,2.94) [0.00,10.00]
Total: 863 W: 488 L: 373 D: 2
http://35.161.250.236:6543/tests/view/5c24b2ea6e23db2472895639

giveaway STC
LLR: 2.95 (-2.94,2.94) [-10.00,5.00]
Total: 1213 W: 398 L: 356 D: 459
http://35.161.250.236:6543/tests/view/5c249ba06e23db2472895636

giveaway LTC
LLR: 2.99 (-2.94,2.94) [-10.00,5.00]
Total: 801 W: 268 L: 223 D: 310
http://35.161.250.236:6543/tests/view/5c24d7466e23db247289563c

diff --git a/src/search.cpp b/src/search.cpp
index 3b2ef90..1cf1720 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -758,6 +758,7 @@ namespace {
         &&  ss->staticEval >= beta - 36 * depth / ONE_PLY + 225
         && !excludedMove
         &&  pos.non_pawn_material(us)
+        && (pos.pieces(~us) ^ pos.pieces(~us, PAWN))
         && (pos.pieces() ^ pos.pieces(BREAKTHROUGH_PIECE) ^ pos.pieces(CLOBBER_PIECE))
         && (ss->ply >= thisThread->nmpMinPly || us != thisThread->nmpColor))
     {