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Subject: Re: Rep detection question

Author: Tim Foden

Date: 23:29:40 04/21/02

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On April 21, 2002 at 19:29:39, Will Singleton wrote:

>All,
>
>[D]5nk1/2R3p1/r4p2/4P3/p2R2N1/7P/1r4P1/7K b - - 0 42
>
>The question is, my prog wants to play a3, and doesn't see the forced repetition
>until ply 9.  I've just thrown away my old buggy rep code, and replaced it with
>a dedicated hash table.  The new stuff seems to be debugged and working (maybe),
>but there must be a trick to getting this position earlier.  An extension,
>perhaps?

Green Light sees this at 5 ply.  The line it gives is:
42... a3 43. Nxf6+ gxf6 44. Rg4+ Kh8 45. Rh4+ Kg8 46. Rg4+

The only extension used here is a check extension x 4, which gets it to the
required 9 ply.  The other trick, of course, is that GL considers it a draw if
the position occurs twice in the current search.

>
>Will



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