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Subject: Re: Draw due to lack of blockade detection...

Author: Omid David

Date: 12:39:36 10/04/02

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On October 04, 2002 at 15:17:45, Joachim Rang wrote:

>On October 04, 2002 at 14:39:05, Vincent Diepeveen wrote:
>
>>On October 04, 2002 at 14:34:46, Joachim Rang wrote:
>>
>>>On October 04, 2002 at 14:21:16, Vincent Diepeveen wrote:
>>>
>>>>On October 04, 2002 at 11:48:06, Omid David wrote:
>>>>
>>>>How many times must i say the same thing?
>>>>
>>>>Suppose i have 200 patterns to adjust my score.
>>>>
>>>>Now 1 pattern can undo all those 200 patterns.
>>>>
>>>>I'm then either an idiot then to have those 200 patterns,
>>>>or to use that one pattern, if it is in 50% of the cases wrong.
>>>>Even if it is in 80% of the cases right :)
>>>
>>>I can't understand what you are trying to say.
>>>Suppose you have 200 patterns and add another drawing-detection pattern a la
>>>Omid. This 201st pattern overrides the 200 other patterns if certain
>>>circumstances are met (which means in certain positions). The pattern does not
>>>change any evaluation if certain circumstances aren't met. Suppose you can
>>>describe the circumstances correctly, the drawing pattern overrides the 200
>>>other patterns only in the correct positions. The other 200 patterns you need
>>>for the other positions.
>>>
>>>regards
>>>
>>>Joachim
>>
>>You still think chess is like mathetmatics, so
>> 1 = 1
>>
>>and
>>
>> 2 = 2
>>
>>then whey aren't there engines playing perfect chess?
>
>yes you may be right, I'm quite a newbie in computer chess and a weak player
>too. But why are you angry at me, instead of telling me, where I don't see the
>point (which should be a bit more concrete than "you are to stupid to understand
>it").

The fact that you are a newbie doesn't have anything to do with this case. Your
reasoning was completely correct.

I'm telling you, there *is* a way to detect blockades with 100% accuracy, i.e.
there might be blockades in which it doesn't detect and that's fine (you'll do
regular search), but it *never* announces draw wrongfully.

It *can* be done, for I have done it, and I believe most of the programmers here
(including Vincent, if he thinks a little before announcing it "impossible") can
do it.


>
>If I understand you correctly you doubt that there is a way to detect such draws
>100% correctly. Okay I'm not an expert in this area you may be right.
>
>>
>>> >
>>>>>On October 04, 2002 at 11:34:39, Vincent Diepeveen wrote:
>>>>>
>>>>>>On October 04, 2002 at 11:26:51, Omid David wrote:
>>>>>>
>>>>>>slowing down the search is not the problem. the problem i
>>>>>>explained in email to sargon
>>>>>
>>>>>So I assume the problem is that it's not 100% reliable, and may return
>>>>>inaccurate estimates. Right?
>>>>>
>>>>>
>>>>>>
>>>>>>>On October 04, 2002 at 11:22:05, Vincent Diepeveen wrote:
>>>>>>>
>>>>>>>>On October 04, 2002 at 10:34:43, Omid David wrote:
>>>>>>>>
>>>>>>>>had fritz implemented such a scheme it would play 300 points weaker
>>>>>>>>anyway.
>>>>>>>
>>>>>>>It depends on how you implement it without slowing down the search
>>>>>>>significantly, and that's what I'm currently working on...
>>>>>>>
>>>>>>>It's obvious that applying the whole heuristic on each and every node is too
>>>>>>>expensive. But a wise application of it, could detect many draws without any
>>>>>>>significant impact on the total speed.
>>>>>>>
>>>>>>>Omid.
>>>>>>>
>>>>>>>
>>>>>>>>
>>>>>>>>>Just today we had a discussion regarding the importance of blockade draw
>>>>>>>>>detections http://www.talkchess.com/forums/1/message.html?255950
>>>>>>>>>
>>>>>>>>>Had Fritz implemented such a scheme, it wouldn't have stepped into the drawing
>>>>>>>>>variation.
>>>>>>>>>
>>>>>>>>>My engine instantly announced draw based on its blocked-draw detection
>>>>>>>>>heuristic. While Fritz never realized the draw...
>>>>>>>>>
>>>>>>>>>Omid.



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