Adjust history threshold for quiet moves futility pruning

Vizvezdenec · snicolet · commit c44c62efc24f · 2020-06-13T06:48:58.000+02:00
This patch adjusts the threshold for futility pruning of quiet moves using the continuation history array contHist[5], in the same way as it is used in movepicker. passed STC: https://tests.stockfishchess.org/tests/view/5ee3f88bca6c451633a9959f LLR: 2.94 (-2.94,2.94) {-0.50,1.50} Total: 55984 W: 10822 L: 10552 D: 34610 Ptnml(0-2): 952, 6435, 12941, 6719, 945 passed LTC: https://tests.stockfishchess.org/tests/view/5ee4186dca6c451633a995cf LLR: 2.96 (-2.94,2.94) {0.25,1.75} Total: 41712 W: 5402 L: 5114 D: 31196 Ptnml(0-2): 293, 3766, 12469, 4016, 312 closes #2734 Bench: 4715960
diff --git a/src/search.cpp b/src/search.cpp
@@ -1006,7 +1006,8 @@ namespace {
                   && ss->staticEval + 235 + 172 * lmrDepth <= alpha
                   &&  (*contHist[0])[movedPiece][to_sq(move)]
                     + (*contHist[1])[movedPiece][to_sq(move)]
-                    + (*contHist[3])[movedPiece][to_sq(move)] < 27400)
+                    + (*contHist[3])[movedPiece][to_sq(move)]
+                    + (*contHist[5])[movedPiece][to_sq(move)] / 2 < 31400)
                   continue;
 
               // Prune moves with negative SEE (~20 Elo)
