Fail-Low

toc
 * Home * Search * Alpha-Beta * Fail-Low**

There are two related semantics, if talking of a **Fail-Low** - inside the search tree or if using aspiration windows at the root.

=Inside the Tree= A **Fail-low** appears at so called All-Nodes inside the alpha-beta algorithm, also called Fail-Low nodes. The score returned is a upper bound on the exact score of the node.

Quote by Bruce Moreland :

=Root with Aspiration= Another meaning of a **Fail-Low**, is associated with aspiration windows at the root, where one needs to re-search with wider windows to get the true score rather than an upper bound.

Bruce again:

=See also=
 * Fail-High
 * Upper Bound
 * Lower Bound
 * Exact Score
 * Move Ordering
 * Null Window

=Forum Posts=

1995 ...

 * [|Failing low at the root] by Guido Schimmels, CCC, August 03, 1998
 * [|Question: Fail High then Low at Root] by William Bryant, CCC, December 28, 1999 » Fail-High, Root, Search Instability

2000 ...

 * [|Question: Fail low at root and time management] by William Bryant, CCC, February 08, 2000 » Root, Time Management
 * [|Fail-Low ?] by Nobuhiro Yoshimura, CCC, April 05, 2000
 * [|Researching after a fail-low] by J. Wesley Cleveland, CCC, August 17, 2000
 * [|Fail highs..which subsequently fail low] by Tom King, CCC, August 27, 2000 » Fail-High, Search Instability
 * [|Researching after a deep fail low] by José Carlos, CCC, September 24, 2001
 * [|MTD, IID, fail-low, root-research] by Juergen Wolf, CCC, August 14, 2003 » MTD(f), Internal Iterative Deepening, Root
 * [|Search behavior in a case of root fail high/low] by Sergei S. Markoff, CCC, March 10, 2004 » Fail-High, MTD(f)

2005 ...

 * [|Fail-low pruning] by Tommi Rimpiläinen, CCC, January 17, 2006

2010 ...

 * [|Fail soft vs fail hard] by Sergei S. Markoff, CCC, February 15, 2014 » Fail-Soft, Fail-Hard, Internal Iterative Deepening
 * [|Solving a fail low situation at the root] by Alberto Sanjuan, CCC, November 03, 2014 » Aspiration Windows
 * [|What does "fail low at the root" mean?] by watersky33, OpenChess Forum, December 24, 2014

2015 ...

 * [|Fail low after fail high] by J. Wesley Cleveland, CCC, April 04, 2015 » Fail-High, Search Instability
 * [|Restarting iterative deepening] by Harm Geert Muller, CCC, December 09, 2015 » Aspiration Windows, Iterative Deepening
 * [|(I)ID and PV dropout] by Harm Geert Muller, CCC, June 17, 2017 » Internal Iterative Deepening, Iterative Deepening

=External Links= > media type="youtube" key="y_I8-FUdUWI" > media type="youtube" key="AjnG5bVS76A"
 * [|Programming - Glossary - Fail Low, Fail High] from Bruce Moreland's [|Programming Topics Site]
 * The Beatles - [|I'm Down] (1966), [|YouTube] Video
 * [|Stevie Ray Vaughan] with Jeff Beck and Terry Bozzio - [|I'm Going Down] (1989), [|YouTube] Video

=References= =What links here?= include page="Fail-Low" component="backlinks" limit="40"
 * Up one Level**