Refutation+Table

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The **Refutation Table** is based on a triangular PV-Table utilized in early chess programs with no or only a small transposition table. It is used not only to store and re-use the PV of the best root move, but variants or at least one refutation move of all other root moves, which may be considered during the next iteration of an iterative deepening framework. However that requires a different update of the triangular array even at Cut-nodes at least near the root. Todays modern programs therefor typically abandon the refutation table and rely on transposition table and Killer heuristic.

=History= In 1982, William Fink, author of the Sfinks program, mentions to save two moves of the variation for every root move. Tony Marsland and Jonathan Schaeffer mention refutation tables in their respective papers and both quote Selim Akl's and Monroe Newborn's 1977 paper //The principal continuation and the killer heuristic// as original source.

Tony Marsland
Tony Marsland mentions refutation table in his 1983 paper :

Jonathan Schaeffer
Jonathan Schaeffer describes the refutation tables as follows :

=Publications=
 * Selim Akl, Monroe Newborn (**1977**). //[|The Principal Continuation and the Killer Heuristic]//. 1977 ACM Annual Conference Proceedings
 * William Fink (**1982**). //An Enhancement to the Iterative, Alpha-Beta, Minimax Search Procedure//. ICCA Newsletter, Vol. 5, No. 1
 * Tony Marsland (**1983**). //Relative Efficiency of Alpha-beta Implementations//. IJCAI 1983, [|pdf]
 * Jonathan Schaeffer (**1989**). //The History Heuristic and Alpha-Beta Search Enhancements in Practice//. IEEE Transactions on Pattern Analysis and Machine Intelligence, Vol. 11, No. 11, [|zipped ps], [|pdf]
 * Tsan-sheng Hsu (**2012**). //Transposition Table, History Heuristic, and other Search Enhancements//. [|slides as pdf]

=Postings=
 * [|alpha beta search iterative deepening refutation table] by [|bysreg], [|Stack Overflow], April 26, 2013
 * [|killer trees] by Harm Geert Muller, CCC, February 23, 2015 » Killer Heuristic

=See also=
 * Countermove Heuristic
 * Killer Heuristic
 * Last Best Reply
 * Principal Variation
 * Refutation Move
 * Transposition Table
 * Triangular PV-Table

=References= =What links here?= include page="Refutation Table" component="backlinks" limit="40"
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