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Subject: Re: Is this a mate in 14? - Another Position where Glaurung has problems

Author: Tord Romstad

Date: 06:20:53 02/11/06

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On February 11, 2006 at 09:12:59, Steve Maughan wrote:

>Here's another position where Glaurung 1.0.2 announces a mate that is shorter
>than the optimal.  This is a Mate in 21 yet Glaurung announces Mate in 19.
>
>The problem is almost certainly a hashing problem. How do you store mate values
>in the hash table?  Do you store "distance from root to mate" or "distance from
>current position to mate"?

I store "distance from root to mate".  Because I don't allow transposition table
cutoffs at PV nodes, this rarely causes incorrect mate announcements.  The
exception is endgames with lots of transpositions, like your position.

This problem would be easy to fix, but I have been too lazy so far.  It doesn't
have any influence on playing strength, and therefore has low priority.

Tord



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