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Subject: Re: shredder 8 and weird PVs? (sandro?)

Author: Jaime Benito de Valle Ruiz

Date: 08:24:44 01/18/04

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On January 18, 2004 at 05:53:49, martin fierz wrote:

>i just received my brand-new shredder 8. when using it for analysis in chessbase
>(which is in fact the only thing i use it for), it often gives PVs which are
>completely ridiculous - the first few moves are ok, then one side blunders a
>piece according to the PV, but the evaluation of that line doesn't show it.
>looks like there is a PV bug in shredder 8? is there any fix for this? i find it
>very annoying...
>
>cheers
>  martin

Shredder 7 does a similar thing: I've seen it giving a winning score for white,
and after following the PV in the variation board, you can see white loosing its
queen, its rook... etc, in a completely absurd way, that definitely has nothing
to do with the score it's showing.
Someone suggested that Shredder retrieves the PV from the transposition table,
and since some of the moves in this table are overwritten during analysis, it is
sensible to expect that sometimes you'll get moves that have been discarded
(e.g. by a beta cutoff) instead of the best move that corresponds to the PV.
Before I use an array to update the PV during analysis in my engine, I extracted
the PV the transposition table... and I used to get rubbish PVs. That's maybe
the reason.
Regards,

  Jaime



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