From Chessprogramming wiki
Revision as of 20:53, 8 April 2020 by GerdIsenberg (talk | contribs)
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)
Jump to: navigation, search

Home * Search * Alpha-Beta * Fail-Low

Going down? [1]

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 [2]:

A fail-low indicates that this position was not good enough for us.  We will not reach this position, because we have some other means of reaching a position that is better.  We will not make the move that allowed the opponent to put us in this position. 

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:

You can also talk about failing high and failing low from the root position, if you use an aspiration window. 

See also

Forum Posts

1995 ...

2000 ...

2005 ...

2010 ...

2015 ...

2020 ...

External Links


Up one Level