This also covers the typical back rank mates as well as the rare Boden's Mate. The Epaulette mate with the queen is a quite simple pattern to detect. attacked by pieces from the queen side, but not exclusively by the queen itself, which no longer controls this square after moving.off the boards (in case of border king).The set of up to two possible escape squares is empty, even after playing the queen move.The "mate square" is not indirectly defended by a slider of the king side through the queen.The queen is not absolutely pinned on a direction other than its moving direction.A "mate square" is attacked not only by one queen, but additionally by any other piece, even indirectly due to a battery.A set of all "mating squares" is determined by the intersection of queen attacks with all squares exclusively defended by the opponent king, but not occupied by pawns and pieces of the queen side.Following conditions may be applied conjunctively in an order from cheap to expensive. However, programs with a sophisticated King Safety evaluation and appropriate data-structures like attack and defend maps may detect tactical motives like skewers and some mates "en passant", to either control the search with less strict conditions, or with a Bloom filter like approach, where false positives refer to no mate, to immediate return mate scores for true negatives.Ī queen can often mate close to the opponent king on straight (or less frequent diagonal) adjacent squares, most often in front of a king on the back rank.
#KING AND QUEEN MATE CODE#
Whether the effort and amount of code for Mate at a Glance is worth, is disputed, considering mate threats from null move pruning as well the inconsistency in knowing some mates but not others. A few programmers apply more general, but also likely more complicated and error-prone pattern. Some programmers apply Mate at a Glance only for cheap and simple cases which occur frequently, like obvious back rank mates, some close mates with the queen, and possibly mates with knight like the smothered mate. Some mate pattern were implemented in various programs, as known for instance from Rebel, Chess System Tal, XiniX and IsiChess. Mate at a Glance was introduced in 1978 by John Birmingham and Peter Kent at Advances in Computer Chess 2, as implemented in their Minimax algorithm Tester Master, and published 1980 in the conference proceedings. This is either a direct mate for the side to move or a mate threat, where one needs to defend accordantly rather than to stand pat at a quiescent node. e4 e5 2.Nf3 f6 3.Nxe5 fxe5 4.Qh5+ Ke7 5.Qxe5+ Kf7 6.Bc4+ Kg6 7.Qf5+ Kh6 8.d4+ Qg5 9.Maria Helena Vieira da Silva - Xeque Mate, 1949 Īn attempt to detect positions statically in evaluation, where one side (not necessarily the side to move) has a legal move to checkmate its opponent king. In case if there is a promotion, first write on which square the promotion is, and the choice of the promoted piece is marked only at the end.įor example: d8Q means: On the d file, the Pawn reached the 8th rank and was promoted to Queen. We don't write the name of the Pawn, only where it moves to. This order only changes in case of Pawn moves. For example: Qd5 means: the Queen moves to the d file and to the 5th rank.Įxample: Rxf5 means: the Rook captures an enemy piece on the f file and on the 5th rank. The bottom left-hand corner is called a1 and it's a black square.įirst we write down the name of the piece that moves, that is the symbol of it, which is usually the first letter of the word. The ranks are marked by numbers from bottom to top: 1, 2, 3, 4, 5, 6, 7, 8 The vertical files are marked with 8 letters, from left to right: a, b, c, d, e, f, g, hģ. Write the symbol of the chess pieces with CAPITAL LETTERS: K, Q, R, B, NĢ.
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