Tweak trapped rook penalty

Vizvezdenec · snicolet · commit 0559eba2522a · 2020-01-29T23:38:33.000+01:00
This patch greatly increases the endgame penalty for having a trapped rook. Idea was a result of witnessing Stockfish losing some games at CCCC exchanging pieces in the position with a trapped rook which directly lead to a lost endgame. This patch should partially fix such behavior making this penalty high even in deep endgames. Passed STC http://tests.stockfishchess.org/tests/view/5e279d7cc3b97aa0d75bc1c4 LLR: 2.94 (-2.94,2.94) {-1.00,3.00} Total: 8528 W: 1706 L: 1588 D: 5234 Ptnml(0-2): 133, 957, 1985, 1024, 159 Passed LTC http://tests.stockfishchess.org/tests/view/5e27aee4c3b97aa0d75bc1e1 LLR: 2.95 (-2.94,2.94) {0.00,2.00} Total: 88713 W: 11520 L: 11130 D: 66063 Ptnml(0-2): 646, 8170, 26342, 8492, 676 Closes official-stockfish/Stockfish#2510 Bench: 4964462 ---------------------- Comment by Malcolm Campbell: Congrats! I think this might be a common pattern - scores that seem to mainly apply to the midgame are often better with a similar (or at least fairly big) endgame value as well. Maybe there are others eval parameters we can tweak like this...
diff --git a/src/evaluate.cpp b/src/evaluate.cpp
@@ -145,7 +145,7 @@ namespace {
   constexpr Score ThreatByKing       = S( 24, 89);
   constexpr Score ThreatByPawnPush   = S( 48, 39);
   constexpr Score ThreatBySafePawn   = S(173, 94);
-  constexpr Score TrappedRook        = S( 52, 10);
+  constexpr Score TrappedRook        = S( 52, 30);
   constexpr Score WeakQueen          = S( 49, 15);
 
 #undef S
