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Subject: Re: Should I Hash at the Leaves?

Author: Robert Hyatt

Date: 09:32:48 02/25/99

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On February 25, 1999 at 05:10:19, Ulrich Tuerke wrote:

>
>On February 25, 1999 at 00:35:29, Don Dailey wrote:
>
>>On February 24, 1999 at 17:53:05, Larry Griffiths wrote:
>>
>>>
>>>I have read a few chess papers about hashing.  The ones that I have read
>>>recommend not hashing at the leaves of the tree, but I seem to get better
>>>performance doing it this way. (At least in the opening and middlegame).
>>>Am I missing something or is this recommendation from the stone ages?
>>>
>>>Larry   ~(:->
>>
>>Do what works best.  I hash 4 ply into the quies search but no farther.
>>Why?  Because I ran a lot of timing tests and this was optimum.
>
>Hashing in quiescence seems a little bit tricky to me. Imagine that you are
>generating captures only but you get a non-capture move from the hash table
>probe.
>How do you handle this case, ignore this hit or make this move ?
>
>Uli
>

In Cray Blitz, I ignored the move...

In crafty, I found that hashing q-search vs not hashing q-search made very
little difference (<10%). But when I removed the hash probe code, and then
didn't worry about the hash move and so forth, I was 10% faster, so it was a
'wash'.

I like the not-hashing approach myself, because it means you can search much
longer before overrunning the hash table...

But the best advice is to _always_ test this yourself..  as YMMV

>>
>>Your mileage may vary!
>>
>>- Don



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