The move of a piece A closes the line of a piece B but opens another line of B.

See also: Bi-valve.

Feather, Christopher John

Moultings 7 , 1991

Example: Valve
h#2 2.1... (4+11)

1.Sfg5 Qxe4+ 2.R7d5 Qe8#
1.Seg5 Qxf3+ 2.Qd5 Qc3#

Valve bR-wQ, Valve bQ-wQ.

View in Helpmate Analyzer

FEN: 8/1pbr4/1pk5/1p3Q1K/1Bq1n3/5n2/8/1b1r3B

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