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Subject: Re: Where is Principal Variation?

Author: José Carlos

Date: 01:48:04 11/23/00

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On November 23, 2000 at 04:22:12, Severi Salminen wrote:

>>For mates it is easy.  Just set the length of the PV to ply-1, when you find
>>you have no legal moves at ply.  IE in Crafty, I have a string of moves in
>>the PV array, and a path_length variable that tells me how many moves are
>>in there...
>>
>>This also saves a bit of memory copying as when you back up a PV, you only
>>have to back up the PV array from the current ply to the end of the PV.  The
>>previous ply can add in its move after it chooses what to back up.  Etc...
>
>Thanks! Are there any other situations where things go wrong and do you know how
>to handle them? I was able to fix the mate problem but then I found another
>problem. But let's see what I can do...

  Don't forget the stalemate case, which is almost the same as the checkmate
case.
  Maybe you want to consider the case when a move from the hash table has the
right value to become a PV move, so you don't have a PV below that move in the
tree unless you follow the hash table to find a PV.

  José C.

>Severi



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