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Subject: Re: Another funky hash problem

Author: James Robertson

Date: 19:19:07 08/25/99

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On August 25, 1999 at 12:36:12, Bruce Moreland wrote:

>
>On August 25, 1999 at 04:56:33, Peter McKenzie wrote:
>
>>On August 25, 1999 at 01:29:55, Bruce Moreland wrote:
>>
>>>
>>>On August 24, 1999 at 22:02:33, James Robertson wrote:
>>>
>>>>I was looking at my code and noticed that I never get any cutoffs when there is
>>>>no available hash move.
>>>
>>>I don't understand this.
>>>
>>>> I modifed my code a little, and it sped up, but then I
>>>>noticed tactical problems;
>>>
>>>Are you fixing bugs or trying to make it go faster?  If you were trying to fix
>>>something, why are you checking speed?
>>>
>>>>on a certain test position it never finds a fairly
>>>>obvious move. Anyway, here is my hash code in my search function.
>>>
>>>You aren't sounding like someone who is in control of your code.
>>
>>Such a way with words :-)
>
>Yeah, I sound pretty harsh there, although I tried to soften it in the part you
>snipped.  But it's one area where I'm a little religious.  I think that it is
>important to understand what software is doing, and avoid fixing bugs by
>experimentation.

Absolutely. Unless you know _what_ caused the bug, it isn't fixed.

James

>
>Especially in a chess program.  The things are so volatile because the process
>takes place in a tree, which is hard to debug.  Almost any change will make a
>bug disappear more often than not, meaning that you can "fix" a search bug by a
>change in eval, because the tree shape changes enough that the bug doesn't
>manifest.
>
>It is possible, and I believe necessary, to understand bugs in chess programs.
>It takes a lot of effort sometimes, but it pays off.
>
>bruce



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