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Subject: Re: Q: null move

Author: James Robertson

Date: 18:57:03 08/02/99

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On August 02, 1999 at 10:41:55, Andrew Williams wrote:

>On August 01, 1999 at 21:02:54, Scott Gasch wrote:
>
>>Ouch...
>>
>>I only can search to 4 ply in that position in 60 sec and my null move succeeds
>>about 40% of the time.  I believe this bad performance has sometime to do with
>>my qeval routine and the fact that it considers all captures/promotes.  I think
>>I need to be more selective about captures in the qeval routine.  My program
>>plays f2f3 after 1 minute of thought.  Here's the report (if anyone cares):
>>
>>  total nodes.....................................4588297
>>  time (sec)......................................60.71
>>  rate (nodes/sec)................................75579
>>
>Your program is nearly twice as fast as mine! But I think you're right
>about selectivity in qsearch. This is a lot of nodes for 4 ply. You might
>look carefully at your move ordering as well.
>
>
>>  null move successes.............................73
>>  null move failures..............................117
>>  null move success rate..........................38.42%
>>
>
>Are these the actual figures? If so, I think there is a problem. Why do
>you only try null move 190 times out of 4.5 million nodes? In my program
>it tries null move so long two conditions are satisfied: (a) both sides
>must have at least two Pieces and (b) the last move wasn't a null move.
>In this case, it tries null move in about 70% of non-quiesce nodes. If
>this figure (190) is correct, I think you could be using null move a lot
>more.

I'll add c) side to move not in check.

James

>
>
>>  pawn hash hits..................................4469147
>>  pawn hash misses................................117413
>>  pawn hash success rate..........................97.44%
>
>There's clearly nothing wrong with your pawn hash table! :-) I get a 92%
>hit rate here.
>
>Regards,
>
>Andrew



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