Bonus for a pawn in front of knight/bishop

Idea originated from a post of Don Dailey
on talkchess and reported by Eelco.

This is the last succesful attempt of a long
series of trials (as usually happens, the
'idea' alone is not enough).

Passed both short 15secs TC
LLR: 2.97 (-2.94,2.94)
Total: 7629 W: 1645 L: 1515 D: 4469

And long 60secs TC
LLR: 2.96 (-2.94,2.94)
Total: 10218 W: 1932 L: 1775 D: 6511

bench: 4944581

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index 70c91f8ae7a877d2ffdf6efbf6395120835c2ce9..b6085b7312c49c22389de90a459decdc5a1bb41e 100644 (file)
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -530,10 +530,17 @@ Value do_evaluate(const Position& pos, Value& margin) {
         if (Piece == BISHOP)
             score -= BishopPawns * ei.pi->pawns_on_same_color_squares(Us, s);
 
         if (Piece == BISHOP)
             score -= BishopPawns * ei.pi->pawns_on_same_color_squares(Us, s);
 

-        // Bishop and knight outposts squares
-        if (    (Piece == BISHOP || Piece == KNIGHT)
-            && !(pos.pieces(Them, PAWN) & pawn_attack_span(Us, s)))
-            score += evaluate_outposts<Piece, Us>(pos, ei, s);
+        if (Piece == BISHOP || Piece == KNIGHT)
+        {
+            // Bishop and knight outposts squares
+            if (!(pos.pieces(Them, PAWN) & pawn_attack_span(Us, s)))
+                score += evaluate_outposts<Piece, Us>(pos, ei, s);
+
+            // Pawn in front of knight/bishop
+            if (    relative_rank(Us, s) < RANK_5
+                && (pos.pieces(PAWN) & (s + pawn_push(Us))))
+                score += make_score(16, 0);
+        }

 
         if (  (Piece == ROOK || Piece == QUEEN)
             && relative_rank(Us, s) >= RANK_5)
 
         if (  (Piece == ROOK || Piece == QUEEN)
             && relative_rank(Us, s) >= RANK_5)