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Subject: Re: Q: null move

Author: Andrew Williams

Date: 02:29:33 08/03/99

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On August 02, 1999 at 21:57:03, James Robertson wrote:

>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

Oops! Forgot about that one.

Andrew


>
>>
>>
>>>  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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