Author: Christophe Theron
Date: 14:07:07 10/05/01
Go up one level in this thread
On October 05, 2001 at 03:23:23, Tim Foden wrote:
>On October 04, 2001 at 22:17:04, Christophe Theron wrote:
>
>>On October 04, 2001 at 07:03:14, Tim Foden wrote:
>>
>>>Hi All,
>>>
>>>I decided that I would add a 2nd SEE to GLC to check whether GLC's SEE was
>>>working. I actually ported GCP's Sjeng SEE (that was posted to the forum a
>>>while ago).
>>>
>>>Both SEE routines now agree in most curcumstances, but one's like the following
>>>have cropped up (where they disagree):
>>>
>>>[D]5rk1/1pp2R1p/p1pb4/6q1/3P1p2/2P4r/PP1BQ1P1/5RKN w - - 2 0
>>>
>>>This can be evaluated in 2 ways...
>>>
>>>(1) BxP (+1000) BxB (-3500) R1xB (+3500) QxR (-5500) RxQ (+10000) RxR (-5500)
>>>.........+1000.......-2500........+1000.......-4500........+5500...........0
>>>
>>>>>> value = 0
>>>
>>>(2) BxP (+1000) BxB (-3500) R7xB (+3500) RxR (-5500) RxR (+5500) QxR (-5500)
>>>.........+1000.......-2500........+1000.......-4500.......+1000.......-4500
>>>
>>>>>> value = -2500
>>>
>>>So... on to the questions:
>>>
>>>a) Does anyone's SEE do anything intelligent in these cases?
>>>
>>>b) Is one of these right, and the other wrong? If so, which one?
>>>
>>>c) Do we actually care, as long as the SEE works in the majority of cases?
>>>
>>>Cheers, Tim.
>>
>>
>>
>>I hope you don't mind if I do not answer your question directly (actually I do
>>not know the answer), but my opinion is that the job of designing a strong chess
>>program INCLUDES the work of designing a way to answer this question by a clear
>>YES or NO (or at least answers like "yes it works for me", or "no it does not
>>work for me").
>>
>>I'm pretty sure that nobody out there knows the clear answer to your question,
>>and the same for the upcoming questions that will arise while you develop your
>>program.
>>
>>So my advice would be that you start right now to think about a way to use your
>>computers so that THEY give you an answer.
>>
>>Hope that helps...
>
>It *may* do :)
>
>Seriously though, I understand what you are saying. I believe I have been
>getting towards this idea myself, as I am finding it very difficult to improve
>the strength of my program now. I think I have done all the easy things... I
>now have to actually test each change I make to see if it is a good or bad
>thing.
>
>This was one of the reasons I added a second SEE to GLC (to make sure the first
>one was working!). It turns out that (a) I think it was working, and (b) I
>still don't know this for sure! :)
>
>Cheers, Tim.
I think you are on the right track. I do that myself often: I write a routine in
two totally different ways (an optimized one and an easy one, preferably using
different algorithms and data structures). In debug mode I call both and see if
the results match. That's an incredibly powerful tool for increasing code
reliability. And that's less expensive than spending hundreds of hours trying to
debug a buggy chess program.
Christophe
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