Difference between revisions of "PV Extensions"
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'''PV Extensions''', (PVS Extensions) | '''PV Extensions''', (PVS Extensions) | ||
| − | a technique to extend along the [[Principal | + | a technique to extend along the [[Principal Variation|principal variation]] (PV) to achieve higher [[Depth|search depths]] in the critical part of the [[Search Tree|tree]]. In [[Rebel]], [[Ed Schroder|Ed Schröder]] incremented a counter each time two consecutive [[PV-Move|PV-moves]] were retrieved from the [[Transposition Table|transposition table]], to extend by one [[Ply|ply]] each time the counter is divisible by four <ref>[http://www.top-5000.nl/authors/rebel/chess840.htm#PVS Extension Techniques in REBEL (PVS extensions)] from [http://www.top-5000.nl/authors/rebel/chess840.htm Programmer Corner] by [[Ed Schroder|Ed Schröder]]</ref>. <span id="Multiple"></span>Influenced by observing the principal variations of [[Junior]] during the [[Kasparov versus Deep Junior 2003]] match, [[David Levy]] proposed multiple extensions to treat the often early stable part of a PV as a single ply in 2003 <ref>[[David Levy]] ('''2003'''). ''The State of the Art in Man vs. “Machine” Chess''. [[ICGA Journal]], Vol. 26, No. 1</ref>. To determine the length of the PV, Levy expresses a threshold as a percentage of the total number of nodes searched with the common PV during the previous iteration of the [[Iterative Deepening|iterative deepening]]. |
=See also= | =See also= | ||
Latest revision as of 11:56, 12 May 2018
Home * Search * Selectivity * Extensions * PV Extensions
PV Extensions, (PVS Extensions) a technique to extend along the principal variation (PV) to achieve higher search depths in the critical part of the tree. In Rebel, Ed Schröder incremented a counter each time two consecutive PV-moves were retrieved from the transposition table, to extend by one ply each time the counter is divisible by four [1]. Influenced by observing the principal variations of Junior during the Kasparov versus Deep Junior 2003 match, David Levy proposed multiple extensions to treat the often early stable part of a PV as a single ply in 2003 [2]. To determine the length of the PV, Levy expresses a threshold as a percentage of the total number of nodes searched with the common PV during the previous iteration of the iterative deepening.
See also
Publications
- David Levy (2003). The State of the Art in Man vs. “Machine” Chess. ICGA Journal, Vol. 26, No. 1
Forum Posts
- PV verification heuristic by Peter Jacobi, CCC, July 05, 1998
- Re: PV verification heuristic by Robert Hyatt, CCC, July 06, 1998
- @Ed about PV extension by Peter Fendrich, CCC, July 19, 2007
External Links
References
- ↑ Extension Techniques in REBEL (PVS extensions) from Programmer Corner by Ed Schröder
- ↑ David Levy (2003). The State of the Art in Man vs. “Machine” Chess. ICGA Journal, Vol. 26, No. 1
- ↑ How Rebel Plays Chess as pdf reprint
