Tweak probcut margin for nCheck chess

STC 3check
LLR: 2.97 (-2.94,2.94) [0.00,10.00]
Total: 5912 W: 2839 L: 2658 D: 415
http://35.161.250.236:6543/tests/view/5b71df4f6e23db0fbab0dca6

diff --git a/src/search.cpp b/src/search.cpp
index 61e414b..04c5393 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -801,7 +801,7 @@ namespace {
         &&  depth >= 5 * ONE_PLY
         &&  abs(beta) < VALUE_MATE_IN_MAX_PLY)
     {
-        Value rbeta = std::min(beta + 216 * (1 + (pos.extinction_value() != VALUE_NONE)) - 48 * improving, VALUE_INFINITE);
+        Value rbeta = std::min(beta + 216 * (1 + !!pos.max_check_count() + (pos.extinction_value() != VALUE_NONE)) - 48 * improving, VALUE_INFINITE);
         MovePicker mp(pos, ttMove, rbeta - ss->staticEval, &thisThread->captureHistory);
         int probCutCount = 0;