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Subject: Re: Internal Iterative Deepening (in Crafty)

Author: Steve Maughan

Date: 07:22:04 01/10/99

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On January 10, 1999 at 02:18:42, Larry Griffiths wrote:

>Steve,
>
>I used Iterative Deepening for time control.  My program keeps increaseing
>its max depth and starting another search as long as time remains.
>max depth and start another search.
>
>The other reason I use it is to increase the efficiency of the alpha-beta
>search.  The principle variation of the last iteration is used as a
>"Killer heuristic".  The moves for the next iteration are ordered
>based on the previous iteration.  This tends to increase the number of
>alpha-beta cutoffs.

Larry,

Yes I have come across Iterative Deepening, the technique I was refering to is
INTERNAL Iterative Deepening.  In Crafty, when it comes across a node in the
middle of the search tree that it does not have a hash table value for, it does
a Depth-2 search to try to find a good move for move ordering.  The benefits are
like the ones you outlined.  I was somewhat surprised that it was of benefit as
an internal move ordering technique.  I'll have to write the rest of my Chess
program before I can test the idea :(

Thanks

Steve Maughan




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