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Subject: Re: Couple of chess programming questions: another MTD drawback

Author: Robert Hyatt

Date: 14:48:58 09/10/02

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On September 10, 2002 at 17:10:38, martin fierz wrote:

>On September 10, 2002 at 09:26:14, Eli Liang wrote:
>
>>(3) Reading Aske Plaat's search & re-search paper, it really seems like mtd(f)
>>is something of a magic bullet.  But I note it seems that more programs don't
>>use it than do (for example Crafty).  What is wrong with mtd(f) which Plaat
>>doesn't say?
>
>one more thing: the way MTD is described on http://www.cs.vu.nl/~aske/mtdf.html,
>it stores both upper and lower bounds in the hashtable. making your hashtable
>smaller for a given memory size. IIRC, (but i am quite fuzzy on this...) the
>paper has comparisons of MTD with PVS for the same number of hashtable entries,
>which is the wrong number. he should have compared the algorithms with the same
>size hashtable. i never understood why you needed two bounds. i'm using one & it
>works :-)
>
>aloha
>  martin


The two bounds are only needed if you can't avoid "bouncing" over the true
value so that you have to search from the other side.

If you do it right, this is not necessary, but doing it right is non-trivial
as I mentioned before...



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