Fail-High
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[ Paul Klee - Red Balloon, 1922 [1] There are two related semantics, if talking of a Fail-High - inside the search tree or if using aspiration windows at the root.
Inside the Tree
A Fail-High is associated with a Beta-Cutoff in the alpha-beta algorithm, which appears at so called Cut-Nodes, also called Fail-High nodes. The score returned is a lower bound on the exact score of the node.
Quote by Bruce Moreland [2]:
Root with Aspiration
Another meaning of a Fail-High, is associated with Aspiration Windows at the Root, where one needs to re-search with wider windows to get the true score rather than a lower bound.
Quote by Bruce again:
See also
- Fail-Hard
- Fail-High Reductions
- Fail-Low
- Fail-Soft
- Upper Bound
- Lower Bound
- Exact Score
- Move Ordering
- Null Window
Forum Posts
1995 …
- Question: Fail High then Low at Root by William Bryant, CCC, December 28, 1999 » Fail-Low, Root, Search Instability
2000 …
- “Percentage of fail-highs” question by Daniel Clausen, CCC, January 03, 2000
- Fail highs..which subsequently fail low by Tom King, CCC, August 27, 2000 » Fail-Low, Search Instability
- Q: Fail High percentage by Peter Fendrich, CCC, December 08, 2000
- What means lazy/plain alpha bounding? by Severi Salminen, CCC, February 06, 2001 » Root
- About False Fail Highs, professionals, and MTD searches by Gian-Carlo Pascutto, CCC, April 12, 2002 » MTD(f)
- what does “fail high” mean? by Scott Farrell, CCC, November 29, 2002
- what does “fail high” mean? In the context of iterative deepening by Scott Farrell, CCC, November 30, 2002 » Iterative Deepening
- Hash and first Fail High by Peter Fendrich, CCC, August 14, 2003
- Search behavior in a case of root fail high/low by Sergei S. Markoff, CCC, March 10, 2004 » Fail-Low, MTD(f)
- Fail-high on first move stat (86%) by Michael Henderson, CCC, July 29, 2004 » Move Ordering
2005 …
- Return eval or upper bound? by John Merlino, CCC, October 26, 2009
2010 …
- Fail High nodes by CDaley11, OpenChess Forum, January 14, 2013
- First post (and FailHigh question!) by Natale Galioto, CCC, June 14, 2013 » Fail-Hard, Fail-Soft
- Why lower bound in fail-high? by grandsmaster, OpenChess Forum, September 20, 2014
2015 …
- Fail low after fail high by J. Wesley Cleveland, CCC, April 04, 2015 » Fail-Low, Search Instability
- cut nodes by Folkert van Heusden, CCC, October 18, 2017 » Cut-Nodes
- On failing high and finding mates by Vincent Tang, CCC, February 16, 2019
2020 …
- Searching fail highs shallower.. by Tom King, CCC, March 02, 2020
External Links
References
- ↑ Paul Klee - Red Balloon, 1922, Wikimedia Commons, Solomon R. Guggenheim Museum
- ↑ Programming - Glossary - Fail Low, Fail High from Bruce Moreland’s Programming Topics Site
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