{"schema":"chessgrammar_motif_entry/1","slug":"self-interference","name":"Self-Interference","aka":"self-block · forced self-obstruction","category":{"key":"dynamic","label":"Sequence tactics"},"edition":{"version":"v3.0","year":"2026"},"certified":true,"canonical":"https://chessgrammar.com/motifs/tactics/self-interference","tabs":{"identity":"https://chessgrammar.com/motifs/tactics/self-interference#identity","structure":"https://chessgrammar.com/motifs/tactics/self-interference#structure","examples":"https://chessgrammar.com/motifs/tactics/self-interference#examples"},"citation":"ChessGrammar (2026). Self-Interference. In: ChessGrammar: A reference for chess concepts, Tactics grammar, edition v3.0. Entry cg:self_interference@1. https://chessgrammar.com/motifs/tactics/self-interference","variants":["pawn"],"seeAlso":["interference","forced-discovery","deflection","discovered-attack"],"definition":{"id":"cg:self_interference@1","statement":"A forced reply to check lands one of the defender's own pieces on a square that blocks another of its pieces from a piece it was guarding. The attacker's next move captures the piece that is no longer guarded.","predicate":["The attacker's move gives check. The defending side has only one answer, either an interposition on the checking line or a move by the king itself. That single forced reply lands one of its own pieces on a square that already had another role. A long-range piece of the defending side was using that exact square to guard one of its own pieces further along the same line.","As soon as that piece lands there, it stands across its own side's guard line. It need not block the check, only the guard. The attacker's next move captures the piece that the guard no longer covers.","The defending side never cuts its own guard by choice. The check itself dictates the square where its reply has to land. Whether this motif is present depends only on where that forced square falls."],"diagnosis":"Self-Interference differs from Attraction by what the forced arrival changes. Here the arriving piece blocks the defender's own line. In Attraction it lands on a capture square. In the counter-example shown here, the guarding rook on g1 is absent. The king's forced move onto the g-file therefore interrupts no defensive duty, and no self-interference forms.","maturity":{"state":"stable"},"holotype":{"fen":"6r1/8/p1p1k3/P1B3Rr/1P2pp1P/2P5/7K/6R1 b - - 0 44","move":"h5h4","san":"Rxh4+","line":["h5h4","h2g2","g8g5"],"best_defense":"h2g2","exploit":"g8g5","guard":"g1","screen":"g2","target":"g5","why":"Rxh4+ is a check that the white king can answer only with Kg2. The square g2 lies on the g-file, between White's own rook on g1 and the rook on g5 that it was defending. The forced king move cuts that guard, and Rxg5+ takes the rook."},"nearMiss":{"fen":"6r1/8/p1p1k3/P1B3Rr/1P2pp1P/2P5/7K/8 b - - 0 44","move":"h5h4","san":"Rxh4+","best_defense":"h2g2","exploit":"g8g5","target":"g5","screen":"g2","guard":"g1","why":"The rook on g1 is gone. Rxh4+ still forces Kg2, and the king still lands on the g-file. No friendly rook stands behind it, so the king blocks no guard and the forced move cuts nothing.","delta":"The rook on g1, whose guard the king's forced move was cutting, is removed. Everything else, including the trigger move, is identical.","neighbour":null},"nearMissPending":null,"standing":{"certified":true,"scope":"definition"}},"axes":[{"key":"screen_piece","name":"The identity of the piece the defending side is forced to interpose","values":["pawn"],"nature":"facts","note":"Read on the screening piece of the cut line. Careful -- the same relation the sibling classic-interference motif reads, but here it points at the other army. In a classic interference the cut line runs enemy-guard / our posed piece / enemy victim, so the screening piece is one of ours. Here the line is built from the defender's own forced reply, so all three ends of it -- guard, screen and victim -- belong to the defending side. That is exactly what makes the motif 'self'. So pawn here names their pawn, the one the check forced onto their own guard line, never ours. The axis has a single value because an earlier second value was withdrawn as a constant alias of the parent, true on all of its occurrences and discriminating nothing."}],"summary":"A defender is forced to interpose, and the interposition cuts one of its own defensive lines."}