Changes

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A '''Legal Move''' is a [[Pseudo-Legal Move|pseudo-legal move]] which does not leave its own [[King|king]] in [[Check|check]]. If not in check, most programs delay the legality test to the child node, after [[Incremental Updates|incremental updates]] [[Attack and Defend Maps|attack and defend maps]] or an explicit [[Square Attacked By|square attacked test]] direct after [[Make Move|make move]]. Earlier programs were even more "lazy", to determine illegal moves after an illegal king capture, while many programs consider [[Pin#AbsolutePin|absolutely pinned]] pieces in [[Move Generation|move generation]] and also for [[Evaluation|evaluation]] purpose, or even perform a strictly legal generation to demand searching legal positions. If in check, most programs apply a special move generator to omit the majority of illegal moves.

* [http://www.open-chess.org/viewtopic.php?f=5&t=2697 En-passant legality test] by tetra, [[Computer Chess Forums|OpenChess Forum]], August 07, 2014 » [[En passant]]

* [http://www.talkchess.com/forum/viewtopic.php?t=63090 TTMove legality checking ? & Killers Move Format?] by [[Mahmoud Uthman]], [[CCC]], February 08, 2017 » [[Hash Move]], [[Killer Move]]

=References=

'''[[Moves|Up one Level]]'''