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

Author: James Robertson

Date: 12:28:19 05/04/99

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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



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