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Subject: Re: How do other programs handle check extensions?

Author: Will Singleton

Date: 15:32:29 05/04/99

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On May 04, 1999 at 15:28:19, James Robertson wrote:

>On May 04, 1999 at 15:03:08, Will Singleton wrote:
>
>>
>>On May 04, 1999 at 13:07:42, KarinsDad wrote:
>>
>>>On May 04, 1999 at 12:40:05, Andrew Williams wrote:
>>>
>>>>On May 04, 1999 at 11:26:29, KarinsDad wrote:
>>>>
>>>>>I was wondering how deeply most programs extended the search at a given ply for
>>>>>check.
>>>>>
>>>>>I implemented singular extensions, check extensions, and capture extensions into
>>>>>my code last night, but ran into the problem of check extensions potentially
>>>>>expanding the extensions into near infinity.
>>>>>
>>>>>How many checks do most programs consider is enough when extending?
>>>>>
>>>>>Thanks,
>>>>>
>>>>>KarinsDad :)
>>>>
>>>>My program simply says "if the iterative deepener started this search
>>>>with depth=D, don't extend beyond 2*D". This is a naive approach, and
>>>>I'd also be interested in hearing what anyone else does.
>>>
>>
>>Sometimes the simple approach is the best.  In mine (which I'm sure is not the
>>best), I simply limit total extensions to 6 beyond depth.  But I also consider
>>some checks in the qsearch.
>>
>>
>>>Yes, this sounds naive since I especially do not want to check 14 ply down when
>>>I am currently searching Ply 14. I was thinking more along the lines of 8 ply
>>>(if you do not get an advantage within 4 moves, then maybe it isn't worth
>>>checking), but I am not sure.
>>>>
>>>>>
>>>>>PS. Will, we realized that our nps is way off. We were compiling the code in
>>>>>debug mode as opposed to optimized mode. So, our 100 knps went up to 209 knps.
>>>>>Duh!
>>>>
>>>>209knps!! What position?
>>>
>>>This is on a P3 400 Mhz with super simple material evaluation code (for a lot of
>>>positions, the program is still real stupid). It will drop in half at least once
>>>I really implement the evaluation.
>>>
>>>>
>>>>Andrew
>>
>>The most nps I get is around 90k, in the endgame.  Avg around 60k on a mac 300.
>>Even with a material only eval, I don't approach your numbers.  You must be
>>doing something right!
>>
>>btw, it's possible that you'll see reduced node counts due to increased cutoffs
>>when you add some positional stuff.
>>
>>Will
>
>On my P233 I get about 120k NPS in most middlegame positions. In the endgame, I
>get 200-270k NPS. With material only, I got greater than 300k.
>
>James

What search method do you use?  And is it bitboard-based?

Will



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