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Subject: Re: Completely blocked positions, some interesting things

Author: Omid David

Date: 19:07:38 10/03/02

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On October 03, 2002 at 21:30:56, Jeremiah Penery wrote:

>On October 03, 2002 at 20:39:02, Omid David wrote:
>
>>On October 03, 2002 at 20:29:28, Jeremiah Penery wrote:
>>
>>>On October 03, 2002 at 19:39:27, Omid David wrote:
>>>
>>>>BTW, how much (in percentage or NPS) did the implemented draw detection slow
>>>>down the engine?
>
>>> The only difference in the two benches below is the blocked-position draw
>>>detection.
>
>>>With detection:
>>>Total nodes: 69410117
>>>Raw nodes per second: 708266
>>>Total elapsed time: 98
>>>
>>>Without:
>>>Total nodes: 69410117
>>>Raw nodes per second: 715568
>>>Total elapsed time: 97
>
>>Quite impressive, just 1.02% slower (paractically negligible). Do you invoke
>>that detection at every node in the search tree?
>
>Yes, but most of the time it exits very quickly (a couple of 'if' clauses).  I
>could probably make it cost even less, but I'm not very interested in doing that
>yet.

But the problem may arise in the endgames where there are a number of pawns and
pieces left which can potentially cause a "block draw". Then in the draw
detection heuristic, almost in every node you'll pass the first few 'if's and
will have to step into a detailed assessment of the position. How much does it
slow down there, in comparison to the non-detecting version?





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