{"schema":"chessgrammar_motif_entry/1","slug":"fork","name":"Fork","aka":"double attack","category":{"key":"motif","label":"Direct tactics"},"edition":{"version":"v3.0","year":"2026"},"certified":true,"canonical":"https://chessgrammar.com/motifs/tactics/fork","tabs":{"identity":"https://chessgrammar.com/motifs/tactics/fork#identity","structure":"https://chessgrammar.com/motifs/tactics/fork#structure","examples":"https://chessgrammar.com/motifs/tactics/fork#examples"},"citation":"ChessGrammar (2026). Fork. In: ChessGrammar: A reference for chess concepts, Tactics grammar, edition v3.0. Entry cg:fork@1. https://chessgrammar.com/motifs/tactics/fork","variants":["absolute","bishop","double","family","grand","king","king_rook","knight","pawn","promotion","queen","queen_rook","relative","rook","royal","triple"],"seeAlso":["skewer","discovered-attack","overloading"],"definition":{"id":"cg:fork@1","statement":"A single piece menaces two or more enemy pieces at once. Against the best defence they cannot all be saved, so the move wins material.","predicate":["After the move, one allied piece, the forker, attacks at least two enemy pieces from its square. At least one of those attacks is newly created by the move itself.","The threat must be effective. The effective target set keeps only menaced pieces whose fall yields something, and the king is always included when geometrically targeted. Fewer than two effective targets rule out a fork, and that residue belongs to Hanging Piece or Trapped Piece.","The gain must hold against best defence. No clean resolution of the multi-threat exists, and the judged outcome is positive. A double attack whose forker can be captured, or whose targets can all be saved, is ruled out and never counted as a fork."],"diagnosis":"A Fork requires two conditions. One piece must attack at least two effective targets, and at least one target must remain lost after the best defence. A single vulnerable target may instead be Hanging or Trapped. A position in which every target can be saved is not a Fork. In the counter-example shown here, only one target remains.","maturity":{"state":"stable"},"holotype":{"fen":"7k/1pr5/8/8/4Pr2/2N4P/6PK/8 w - - 0 1","move":"c3d5","san":"Nd5","forker":"d5","targets":["c7","f4"],"why":"The knight lands on d5 and menaces two rooks at once, on c7 and f4. They cannot both be saved, and the best defence Rf7 concedes the exchange on f4. One piece, two effective targets and a gain held against the best defence make this exactly a Fork."},"nearMiss":{"fen":"7k/1pr2r2/8/8/4P3/2N4P/6PK/8 w - - 0 1","move":"c3d5","san":"Nd5","delta":"The rook moves from f4 to f7, out of the knight's reach. Everything else, including the trigger move, is identical.","why":"From d5 the knight now attacks a single enemy piece, the rook on c7. With fewer than two targets attacked, no fork exists. One attacked piece is a matter of Hanging or Trapped, never of Fork.","neighbour":"none"},"nearMissPending":null,"standing":{"certified":true,"scope":"definition"}},"axes":[{"key":"piece","name":"The forking piece's type","values":["knight","pawn","queen","bishop","rook","king","promotion"],"nature":"facts","exclusive":[["knight","pawn","queen","bishop","rook","king"]],"note":"Read off the forking piece's type -- a pure fact; promotion is a mechanism fact about the trigger move, grouped on this same axis."},{"key":"targets","name":"Composition of the effective target set","values":["royal","family","grand","king_rook","queen_rook","double","triple","absolute","relative"],"nature":"facts","note":"Ordered specific-before-generic: named composition (royal, family, grand), then named pair (king-rook, queen-rook), then count (double, triple), then check/non-check (absolute/relative -- an exact partition, exactly one of the two on every fork, placed last so nothing is masked by it)."}],"summary":"A single piece attacks two or more targets at once, so the defender cannot save them all."}