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Subject: Re: Null Move Hash Table Issues

Author: Andrew Platt

Date: 08:25:16 09/09/04

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On September 09, 2004 at 10:03:03, Chris Welty wrote:

>On September 09, 2004 at 09:45:08, Andrew Platt wrote:
>
>>4r1k1/p1qr1p2/2pb1Bp1/1p5p/3P1n1R/1B3P2/PP3PK1/2Q4R w - -
>>
>>You may recognize this as WAC 141 (again!). The key move is Qxf4! which I spot
>>at iterate ply 9, though I don't see the mate there because the search drops
>>into the quiescent search where I don't see the final move Rh8# (I don't
>>generate / deal with checks in qsearch).
>>
>>So we back up non-mate scores which, as expected, end up in the hash table -
>>including the following:
>>
>>Qxf4 Be5 Rxh5 Bxf4 (ply 4, depth 270)
>
>If this position was searched with remaining depth>0 it should be in your
>hashtable as mate in 1. If it was searched with remaining depth=0 it should be
>too shallow to impact your null-move search.

Hmm, you're right: Qxf4 Be5? Rxh5 Bxf4?? Rh8#  I'll have to check how we're
backing up a non-mate score there.

Andy.



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