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Subject: Re: General Tips and Tricks for debugging a search.

Author: Vincent Diepeveen

Date: 15:14:49 06/16/05

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On June 16, 2005 at 03:50:17, Ed Schröder wrote:

>On June 15, 2005 at 16:36:54, Eric Oldre wrote:
>
>>I was wondering if anyone would like to volunteer any tricks they've
>>used to help find certain bugs in their search function.
>>
>>I think that the ideas of using perft for move generation and
>>reversing the board to find bugs in the evaluation have both
>>been really useful to me. I was wondering if anyone has used
>>techniques similar to these to help find search bugs.
>>
>>I understand that just because a engine can properly pass these
>>and other tests doesn't mean it's free of bugs. But they certainly
>>help detect at least some of them.
>>
>>I'm certain that there must be plenty of bugs in Latista's search
>>and I think it's time for me to work on discovering them. If
>>you don't have any automated tricks like above. Does anyone
>>have any general advise to help me spot some bugs?
>>
>>Eric Oldre
>>
>>PS. I have at various spots in my program tried to follow a similar
>>model of asserts as in fruit. I'm sure taking some time to
>>do this at more parts of my program would help.
>
>
>As an addition to all the hints of others consider a piece of software that sets
>a breakpoint based on the move list.
>
>[d]Rnk1r2r/1p1b2p1/1Pq1p1n1/2Ppp1p1/1QP5/5N2/5PPP/5RK1 w - -
>
>Say your program can't find the easy 1.Rxb8+ Kxb8 2.Ra1! within a reasonable
>depth then set a breakpoint on 2.Ra1 and then go step by step through the search
>(for instance) by the space bar in the meantime displaying all the relevant
>information on the screen.
>Ed

Oh well, i might be doing that far faster. I just walk through the hashtable
what move gave a cutoff for Ra1.

In such a case i can skip slow debugging with the debugger. I see in 5 seconds
the problem from the hashtable in such a case.

Vincent



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