Extend last non-pawn captures at principal variation nodes because
they are in general decisive moves with clear endgame result.
STC
http://tests.stockfishchess.org/tests/view/
5ddafc86e75c0005326d2140
LLR: 2.96 (-2.94,2.94) [-1.50,4.50]
Total: 9892 W: 2238 L: 2099 D: 5555
LTC
http://tests.stockfishchess.org/tests/view/
5ddb0401e75c0005326d2150
LLR: 2.95 (-2.94,2.94) [0.00,3.50]
Total: 30369 W: 5013 L: 4756 D: 20600
Closes https://github.com/official-stockfish/Stockfish/pull/2425
Bench:
5059526
&& pos.pawn_passed(us, to_sq(move)))
extension = 1;
&& pos.pawn_passed(us, to_sq(move)))
extension = 1;
+ // Last captures extension
+ else if ( PvNode
+ && PieceValue[EG][pos.captured_piece()] > PawnValueEg
+ && pos.non_pawn_material() <= 2 * RookValueMg)
+ extension = 1;
+
// Castling extension
if (type_of(move) == CASTLING)
extension = 1;
// Castling extension
if (type_of(move) == CASTLING)
extension = 1;