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Subject: Re: extensions

Author: Dave Gomboc

Date: 16:26:27 08/18/99

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On August 18, 1999 at 18:49:47, Andrew Williams wrote:

>On August 18, 1999 at 17:57:01, Scott Gasch wrote:
>
>>Hi there,
>>
>>By converting from standard negamax to a negascout search I made a dent in the
>>move branching factor and the program is searching deeper.  I also got razoring
>>working.
>>
>>However razoring is kinda stupid without extensions and whenever I add
>>extensions to the search routine the program slows _way_ down.  I think the most
>>common extension is a check extension that is what I am implementing now.  So if
>>side to move is in check I am calling the recursive search routine with the
>>depth unadjusted...  This is 1000% slower than no check extensions :(
>>
>>So I tried a thing that I don't understand completely but I see Crafty do and
>>have heard about before -- now my depth for one ply is 16 and I try fractional
>>extensions for check.  This still slows the program down a lot.
>>
>>I originally thought this might be because of repeated positions and branches of
>>the tree going back and forth until the 50 move draw rule cut them off.  However
>>I just added a draw by repetition check that seems to work and still when I turn
>>on extensions it is  s l o w.
>>
>>Does anyone have any thoughts about the pitfalls of extension that I might be
>>falling into?
>>
>>Thanks again for the help.
>>
>>Scott
>
>Hi Scott,
>
>Can you give an example position, together with your "before" and "after"
>search info? This helps a lot in diagnosis and helps promote discussion.
>
>Cheers
>
>Andrew

Tell us the name of your program too!  How long have you been working on it?

Dave



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