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Subject: Re: What means lazy/plain alpha bounding?

Author: Ernst A. Heinz

Date: 13:57:37 02/06/01

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Hi Severi,

>What means lazy and plain alpha bounding as used in DarkThought?
>These names are used in Heinz's book but not described. Thanks for info.

Actually there is a very brief explanation and a literature reference
to Jonathan Schaeffer's Ph.D. thesis on page 191 of my book. Basically,
alpha bounding accepts new best moves found by minimal-window searches
in a PVS setting "as is" and delays the resolution of their real values
until the next iteration. I quote the book text below.

-----

`` At the top level, DARKTHOUGHT employs lazy alpha bounding and
   iterative deepening with an aspiration window of half a Pawn [131,201].
   In contrast to plain alpha bounding [192], the lazy scheme delays the
   complete resolution of both new best moves and fail highs up to the next
   iteration. Top-level alpha bounding often saves some effort while at the
   same time searching new best moves one ply deeper than usual. ''

-----

Please visit my WWW pages at http://supertech.lcs.mit.edu/~heinz/
for further information.

=Ernst=



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