{"schema":"chessgrammar_motif_entry/1","slug":"forced-mate","name":"Forced Mate","aka":null,"category":{"key":"mate","label":"Checkmates"},"edition":{"version":"v3.0","year":"2026"},"certified":false,"canonical":"https://chessgrammar.com/motifs/mats/forced-mate","tabs":{"identity":"https://chessgrammar.com/motifs/mats/forced-mate#identity","structure":"https://chessgrammar.com/motifs/mats/forced-mate#structure","examples":"https://chessgrammar.com/motifs/mats/forced-mate#examples"},"citation":"ChessGrammar (2026). Forced Mate. In: ChessGrammar: A reference for chess concepts, Mates grammar, edition v3.0. Entry cg:forced_mate@1. https://chessgrammar.com/motifs/mats/forced-mate","variants":["mate_in_2","mate_in_3","mate_in_4","mate_in_5"],"seeAlso":[],"definition":{"id":"cg:forced_mate@1","statement":"A legal move that leads to checkmate against every legal reply of the defender, each followed under its best defense, within a fixed number of moves. A threat that beats one reply but fails against another does not qualify.","predicate":["The move is legal from the position. For every legal reply of the defender, exhaustive search, not a heuristic, proves that checkmate is forced under the defender's own best resistance.","The total count of the attacker's own moves, including the announcing move, is between two and five. A mate delivered by the move played, a mate in one, needs no defender reply and lies outside the depths grouped under this motif."],"diagnosis":"Forced Mate differs both from a mate threat and from Checkmate. A mate threat fails if any legal defence avoids mate. Forced Mate survives every legal reply. Checkmate is already a terminal state, so it has no remaining depth. In the counter-example shown here, the candidate move does not force mate in two. This does not exclude a later mate at another depth.","maturity":{"state":"stable"},"holotype":{"fen":"r1bq3r/pp1nbkp1/2p1p2p/8/2BP4/1PN3P1/P3QP1P/3R1RK1 w - - 0 20","move":"e2e6","san":"Qxe6+","n":2,"line":["e2e6","f7e8","e6f7"],"why":"White plays 20.Qxe6+, capturing with check the pawn that shields the black king. Black has two legal replies, and each permits mate one move later. In the line shown, the king goes from f7 to e8, where 21.Qf7# completes the announced mate in two."},"nearMiss":{"fen":"r1bq3r/pp1nbkp1/2p1p2p/8/2BP4/1PN3P1/P3QP1P/3R1RK1 w - - 0 20","move":"d1e1","san":"Rde1","delta":"The position is unchanged. White plays the quiet rook move Rde1 instead of the mating Qxe6+.","why":"Rde1 does not check the black king and does not restrict any of its squares. The defender can answer with any of its ordinary replies, and none of them is forced into checkmate one move later. The board looks the same and a queen capture is still available, but this move does not force anything.","neighbour":"none"},"nearMissPending":null,"standing":{"certified":true,"scope":"definition"}},"axes":[{"key":"depth","name":"Number of the attacker's own moves needed to force mate, counting the announcing move","values":["in_2","in_3","in_4","in_5"],"nature":"partition","note":"Four values, an exact partition over the four depths mate-in-2 through mate-in-5: a genuinely forced mate is proven at exactly one of these depths by the best-defense search, never two at once. Mate-in-1 is excluded from this motif entirely -- it has no defender reply to force."}],"summary":"A forced sequence of moves that ends in checkmate against every legal defence at each branch."}