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Subject: Re: Maybe I understand better now ....

Author: Dan Homan

Date: 04:41:23 10/04/98

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On October 04, 1998 at 01:38:11, Bruce Moreland wrote:

>
>On October 03, 1998 at 12:07:46, Dan Homan wrote:
>
>>
>>On October 02, 1998 at 17:38:47, Bruce Moreland wrote:
>>
>>>
>>>On October 02, 1998 at 16:19:08, Dan Homan wrote:
>>>
>>>>On the idea of a 'dumb as a rock' qsearch.... Mine is even dummer.
>>>>I don't use an SEE in the qsearch, but rather simply score the move
>>>>based on the value of the attacked pieces minus the value of the
>>>>attacking piece (if the attacked piece is defended).  This will
>>>>avoid some captures that are sound (because sometimes we have multiple
>>>>attacks on the square), but it is quite fast and leads to a small qsearch.
>>>>I also toss out captures that lose material or don't bring me near
>>>>alpha.
>>>
>>>Basically you'll almost always check P x something, but will almost never check
>>>Q x something, right?
>>
>>Yep.... unless Q x Q or Q x something which is not defended and brings the
>>material score near alpha.
>
>OK, this isn't the pure case then.  The case I just ran a test on, based upon
>your post was something like this:
>
>AxB, where A>B, never try this.
>AxB, where A=B, call it a swap for sorting purposes.
>AxB, where A
>The rest of my program was the same as it always.  The difference between this
>and what I normally do is that I use a static exchange evaluator on these last
>two cases in order to get a more accurate picture of the outcome.
>
>This scored worse on the ECM tactical suite that I always run.  I would report
>the exact number here but it suddenly occured to me that the machine is busy
>running another test, so I can't mess with it.
>
>bruce

Ok, here is exactly what I do.....

score_of_AxB =  score_of_B
if (B is defended)  score_of_AxB -= score_of_A

if score of AxB is >= 0 *and* brings me near alpha then I try the
capture.   I should probably use some additional logic to avoid the
'if (B is defended)' test for cases where it won't matter.

 - Dan



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