- return false;
- }
-
-
- // refutes() tests whether a 'first' move is able to defend against a 'second'
- // opponent's move. In this case will not be pruned. Normally the second move
- // is the threat (the best move returned from a null search that fails low).
-
- bool refutes(const Position& pos, Move first, Move second) {
-
- assert(is_ok(first));
- assert(is_ok(second));
-
- Square m1from = from_sq(first);
- Square m2from = from_sq(second);
- Square m1to = to_sq(first);
- Square m2to = to_sq(second);
-
- // Don't prune moves of the threatened piece
- if (m1from == m2to)
- return true;
-
- // If the threatened piece has value less than or equal to the value of the
- // threat piece, don't prune moves which defend it.
- if ( pos.capture(second)
- && ( PieceValue[MG][pos.piece_on(m2from)] >= PieceValue[MG][pos.piece_on(m2to)]
- || type_of(pos.piece_on(m2from)) == KING))
+ // Increase history value of the cut-off move and decrease all the other
+ // played quiet moves.
+ Value bonus = Value(int(depth) * int(depth));
+ History.update(pos.moved_piece(move), to_sq(move), bonus);
+ for (int i = 0; i < quietsCnt; ++i)