Decrease delta

Vizvezdenec · vondele · commit 930915de901b · 2024-07-15T13:22:31.000+02:00
Decrease delta in aspiration windows - both initial value and quadratic function of previous best value. Passed STC: https://tests.stockfishchess.org/tests/view/6691a52ec6827afcdcee1569 LLR: 2.93 (-2.94,2.94) <0.00,2.00> Total: 55456 W: 14449 L: 14107 D: 26900 Ptnml(0-2): 174, 6416, 14193, 6784, 161 Passed LTC: https://tests.stockfishchess.org/tests/view/6691aac1c6827afcdcee1625 LLR: 2.94 (-2.94,2.94) <0.50,2.50> Total: 107940 W: 27530 L: 27065 D: 53345 Ptnml(0-2): 52, 11787, 29840, 12226, 65 closes official-stockfish#5479 bench 1547707
diff --git a/src/search.cpp b/src/search.cpp
@@ -320,7 +320,7 @@ void Search::Worker::iterative_deepening() {
 
             // Reset aspiration window starting size
             Value avg = rootMoves[pvIdx].averageScore;
-            delta     = 9 + avg * avg / 10424;
+            delta     = 5 + avg * avg / 13424;
             alpha     = std::max(avg - delta, -VALUE_INFINITE);
             beta      = std::min(avg + delta, VALUE_INFINITE);
 
