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Subject: Re: move_generation + hash

Author: Tom Kerrigan

Date: 10:18:09 05/31/00

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On May 31, 2000 at 10:48:50, Robert Hyatt wrote:

>On May 31, 2000 at 01:10:52, Tom Kerrigan wrote:
>
>>On May 30, 2000 at 21:48:52, Robert Hyatt wrote:
>>
>>>>All I'm saying is that the numbers you gave (e.g. 25%) are (hash hits/hash
>>>>probes) and not (hash hits/nodes). The latter is what's more important in this
>>>>case.
>>>>
>>>>-Tom
>>>
>>>
>>>That number would be meaningless.  Of course you can't "hit" if you don't
>>>"probe".  Who would care?  I only want to know what percentage of the time I
>>>get a hit after doing a probe...  which seems like the only reasonable measure
>>>of anything.  If a program probes in the q-search, those numbers would match
>>>mine _exactly_ since in his case, probes == nodes.
>>
>>No, that number would NOT be meaningless.
>>
>
>A number computed from dividing one independent value into another independent
>value is meaningless.  such a hit percentage would be useless unless you compare
>two programs with identical q-searches.  Because you are factoring in q-search
>nodes which has absolutely nothing to do with  the number of hash hits and
>misses I get.  Since I neither hit nor miss in the q-search.

The optimization should not affect the number of nodes searched. So you ARE
working with identical q-searches. And hash hits, for that matter.

>>Sure, if you are trying to gague the effectiveness of a hash entry replacement
>>scheme, it makes more sense to measure hits/probes. But in this case, "we" need
>>to find out how many times the hash move can short-circuit move generation. So
>>unless you don't generate moves in qsearch() either, the number is important.
>>
>>-Tom
>
>
>Why?  The question is does not generating moves save time?  Not "does not
>generating moves only in the normal search save time?" or not "does not
>generating moves only in the q-search save time?"

No, I think you need to go and read the original post.

The question was, "how much faster will I be if I try hash table moves before
generating the rest of the moves?"

So if you only do hashing in "normal" search, then the question IS one of the
latter (sort of).

-Tom



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