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Subject: Re: What is the branching factor for this position?

Author: Tom Kerrigan

Date: 20:37:12 08/11/00

Go up one level in this thread


On August 11, 2000 at 22:45:05, Robert Hyatt wrote:

>On August 11, 2000 at 17:56:02, Tom Kerrigan wrote:
>
>>On August 11, 2000 at 15:49:57, Robert Hyatt wrote:
>>
>>>On August 11, 2000 at 13:48:22, Tom Kerrigan wrote:
>>>
>>>>On August 11, 2000 at 09:09:38, Robert Hyatt wrote:
>>>>
>>>>>On August 10, 2000 at 23:20:42, Tom Kerrigan wrote:
>>>>>
>>>>>>On August 10, 2000 at 21:46:24, Robert Hyatt wrote:
>>>>>>
>>>>>>>Either way will work.  your way is the way suggested by software engineering.
>>>>>>>And your way will have less debugging.  Your way will make it hard to evaluate
>>>>>>
>>>>>>If your program has no check extension and no quiescence search, how is it any
>>>>>>easier to debug?
>>>>>>
>>>>>>-Tom
>>>>>
>>>>>
>>>>>It has less code to go wrong.  I started off writing my move generator and
>>>>>nothing else.  I debugged that until I was sure it worked.  That is far
>>>>>easier than writing the whole thing, then debugging several thousand lines
>>>>>of new and untested code, all at one time.
>>>>>
>>>>>This is why the top-down approach became so popular years ago...
>>>>
>>>>Yes, I also wrote my move generator before anything else.
>>>>
>>>>But Lenoid has written an entire chess program. He simply refuses to put in
>>>>extensions or qsearch.
>>>>
>>>>I think such a program would be harder to debug. Does it play God-awful moves
>>>>because it has no qsearch, or is it due to some bug? Hard to tell.
>>>>
>>>>-Tom
>>>
>>>
>>>I wouldn't argue with that statement at all.  Not having any q-search will lead
>>>to many bogus PVs, obviously.  But once you have a reasonable search, a reason-
>>>able q-search, and a simple eval(), you are set to test and debug for a long
>>
>>Right, Lenoid doesn't have a reasonable q-search.
>>
>>I believe that check extensions are also necessary to avoid horrible
>>horizon-effect moves.
>>
>>-Tom
>
>
>I don't think it is too hard to understand the horizon effect, and notice when
>you see it in your PVs.  IE even search extensions don't eliminate this problem
>so it is useful to become skilled at recognizing the problem anyway, because
>it will happen no matter what you do (maybe less frequently, but less != 0).
>
>I am more concerned about the kind of bugs that cause more subtle and hard
>to reproduce errors.  Horizon effects are easy to see (with experience).  A
>legal move generator that misses the one enpassant way out of check is much
>more difficult to catch.

I never said that check extensions completely eliminate horizon-effect problems.

But if you don't extend when in check, your program will just throw away its
pieces to give check and only later realize that those pieces are useful...

-Tom



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