Enhanced+Transposition+Cutoff

an attempt to get a cutoff from the transposition table, even though an entry may not exist for the current position. Entries may exist for **children** of the current position and one of these could be used to produce a cutoff without having to expand the current node. This is done by looping over the legal moves calculating the hash keys and doing a transposition table lookup with them in the hopes that one of these will produce the desired cutoff. One enhancement of this idea is to try only the strongest moves, perhaps the first several that are deemed to have potential.
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 * [[image:ETC.JPG]] ||~ || **Enhanced Transposition Cutoff** (ETC) ,

In cases where a cutoff cannot be found, a fairly substantial amount of time is wasted, so in general it should not be applied at shallow depths of the tree where the small sub-tree savings may not justify the extra work. Example code for Enhanced Transposition Cutoff is rather difficult to find. One possible source is Fruit version 1.5. However, this technique is not used since version 2.0, as tests have shown that it hurts Fruit's strength. || toc =Maximizing Transpositions= Quote from Aske Plaat, Jonathan Schaeffer, Wim Pijls and Arie de Bruin in //Nearly Optimal Minimax Tree Search?// :
 * ETC at node N ||~ ||^ ||

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=See also=
 * Beta-Cutoff
 * Repetitions
 * Transposition

=Publications=
 * Aske Plaat, Jonathan Schaeffer, Wim Pijls, Arie de Bruin (**1994**). //[|Nearly Optimal Minimax Tree Search?]// Technical Report, University of Alberta
 * Aske Plaat, Jonathan Schaeffer, Wim Pijls, Arie de Bruin (**1996**). //Exploiting Graph Properties of Game Trees.// [|13th National Conference on Artificial Intelligence] ([|AAAI-96]), Vol. 1, pp. 234-239, ISBN 978-0-262-51091-2. [|pdf], [|ps]

=Forum Posts=

1995 ...
> [|Re: Tree search issues!] by Robert Hyatt, rgcc, May 26, 1997 > [|Re: Tree search issues!] by Aske Plaat, rgcc, May 27, 1997
 * [|Hash Table test (re: move ordering)] by Robert Hyatt, rgcc, February 8, 1996
 * [|Trick Marsland] by Robert Hyatt, rgcc, February 15, 1996
 * [|Tree search issues!] by Magnus Heldestad, rgcc, May 26, 1997 » MTD(f)
 * [|ETC hashing discussion] by Robert Hyatt, rgcc, May 28, 1997
 * [|Enhanced Transposition Table Cutoffs] by Andrea Zinno, rgcc, July 30, 1997
 * [|Enhanced Transposition Cutoff] by Peter Fendrich, CCC, May 18, 1998

2000 ...

 * [|Programmers: ETC] by Peter McKenzie, CCC, February 13, 2003
 * [|Enhanced Transposition Cutoff] by Stuart Cracraft, CCC, July 28, 2004

2005 ...

 * [|Enhanced Transposition Cutoff] by kongsian, CCC, April 10, 2007
 * [|Enhanced Transposition Cutoff] by hcyrano, CCC, November 11, 2008

2010 ...

 * [|Mult-cut, SE and ETC] by Ricardo Gibert, CCC, August 05, 2010 » Multi-Cut, Singular Extensions

=References= =What links here?= include page="Enhanced Transposition Cutoff" component="backlinks" limit="40"
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