Hash Move

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The Hash Move is a Move Ordering related issue.

The Hash Move is a move probed from the transposition table, either a best move of a stored PV-node - a PV-move, or a good enough refutation move to cause a cutoff. This move should most importantly searched first. One may save the move generation at all, if the hash move actually fails high. To guard against rare TT key collisions, one may apply a legality test of the hash move.

=See also=
 * Best Move
 * Internal Iterative Deepening
 * Killer Move
 * Mate Killers
 * Move Ordering
 * Null Move
 * Pseudo-Legal Move
 * PV-Move
 * Refutation Move
 * Threat Move from null move refutations
 * Transposition Table
 * Collisions

=Forum Posts=
 * TTMove legality checking ? & Killers Move Format? by Mahmoud Uthman, CCC, February 08, 2017 » Killer Move
 * tt move vs null move by Erin Dame, CCC, May 27, 2017 » Null Move, Null Move Pruning
 * Marginal hash move by Harm Geert Muller, CCC, September 16, 2017
 * Hash move ordering vs. Hash cuts: savings in number of nodes visited by Marcel Vanthoor, CCC, March 16, 2021
 * Best move from previous iteration first: still needed with TT? by Marcel Vanthoor, CCC, March 16, 2021 » PV-Move
 * PV-move ordering necessary if you have TT-move ordering? by Marcel Vanthoor, CCC, July 01, 2021

=References=

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