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A '''Static Exchange Evaluation (SEE)''' examines the consequence of a series of exchanges on a single [[Squares|square]] after a given [[Moves|move]], and calculates the likely evaluation change ([[Material|material]]) to be lost or gained, [[Donald Michie]] coined the term [[SOMA#SwapoffSwapOff|swap-off value]]. A positive static exchange indicates a "winning" move. For example, PxQ will always be a win, since the Pawn side can choose to stop the exchange after its Pawn is recaptured, and still be ahead. Some programs optimize the SEE function to only return a losing or equal/winning flag, since they only use SEE to determine if a move is worth searching and do not need the actual value. SEE is useful in [[Move Ordering|move ordering]], [[Futility Pruning|futility pruning]] and especially in [[Quiescence Search|quiescence search]] in conjunction with [[Delta Pruning|delta pruning]], as well to [[Reductions|reduce]] "bad" [[Captures|captures]] and [[Check|checks]] <ref>[http://www.talkchess.com/forum/viewtopic.php?t=40100 Reducing/Pruning Bad Captures (SEE < 0)] by [[Edsel Apostol]], [[CCC]], August 19, 2011</ref> .