{"schema":"chessgrammar_motif_entry/1","slug":"trapped-piece","name":"Trapped Piece","aka":null,"category":{"key":"constraint","label":"States"},"edition":{"version":"v3.0","year":"2026"},"certified":true,"canonical":"https://chessgrammar.com/motifs/tactics/trapped-piece","tabs":{"identity":"https://chessgrammar.com/motifs/tactics/trapped-piece#identity","structure":"https://chessgrammar.com/motifs/tactics/trapped-piece#structure","examples":"https://chessgrammar.com/motifs/tactics/trapped-piece#examples"},"citation":"ChessGrammar (2026). Trapped Piece. In: ChessGrammar: A reference for chess concepts, Tactics grammar, edition v3.0. Entry cg:trapped_piece@1. https://chessgrammar.com/motifs/tactics/trapped-piece","variants":["bishop","knight","queen","rook"],"seeAlso":[],"definition":{"id":"cg:trapped_piece@1","statement":"A piece other than the king or a pawn has no legal move that avoids a net loss of material. The danger is real, because the piece is already attacked or every square it could move to is attacked.","predicate":["The piece is a knight, bishop, rook or queen, never a king or a pawn. Every one of its legal moves either loses the piece outright or trades it for less than its value. This is judged by a full look-ahead and not by a one-move count. A piece with no legal move at all also qualifies, unless it cannot move only because it is absolutely pinned to its own king. That case belongs to a different motif, Pin.","The danger must come from the opponent. Either the piece is attacked where it stands, or an enemy piece attacks every square it could move to. A piece with no legal move, such as one boxed in by its own pieces, is trapped only if it is attacked where it stands.","Unlike the other motifs in this collection, this motif is a fact about a position on its own and not about a move that produces it. The position already shows the piece with no safe square, whichever side is to move next."],"diagnosis":"Trapped Piece and Pin differ in why the piece cannot move. A trapped piece has no safe square because of opposing control. A pinned piece cannot move without exposing a more valuable piece or the king. Confinement caused only by friendly pieces belongs to neither motif. In the counter-example shown here, the trapped piece is absent, so the condition has no subject.","maturity":{"state":"stable"},"holotype":{"fen":"7r/4k3/2p1pP1r/1p1p2Np/p2P1P2/2P2K1R/8/R7 b - - 0 74","move":"e7f6","san":"Kxf6","line":["e7f6"],"piece":"g5","piece_type":"knight","victim":"white","why":"Black's king captures the pawn on f6 and attacks the knight on g5. Every square the knight could reach is covered or occupied. The pawn on f4 guards the knight for now, but the knight can never leave, so it is lost to a second attacker. The trap holds after this king move, which does not capture the knight."},"nearMiss":{"fen":"7r/4k3/2p1pP1r/1p1p3p/p2P1P2/2P2K1R/8/R7 b - - 0 74","move":"e7f6","san":"Kxf6","line":[],"piece":"h8","piece_type":"rook","victim":null,"delta":"The knight on g5 is removed. Everything else, including the trigger move, is identical.","why":"The knight on g5 is gone, so Kxf6 wins a pawn and touches nothing else. Every other piece stands where it stood, and every square that was closed to the knight is still closed. No piece is boxed in there, so there is nothing to trap.","neighbour":null},"nearMissPending":null,"standing":{"certified":true,"scope":"definition"}},"axes":[{"key":"piece","name":"The nature of the trapped piece","values":["bishop","knight","queen","rook"],"nature":"partition","note":"Four values, read off the trapped piece's type -- an exact partition: mutually exclusive by construction, since a piece has exactly one type. Never a king or a pawn, both excluded by the parent motif itself."}],"summary":"A piece with no safe square, so it can be won wherever it goes."}