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Subject: Re: right now, at this very moment wac 141?

Author: Robert Hyatt

Date: 07:15:31 10/01/04

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On October 01, 2004 at 03:00:25, Uri Blass wrote:

>On October 01, 2004 at 00:01:02, Robert Hyatt wrote:
>
>>On September 30, 2004 at 23:02:42, Uri Blass wrote:
>>
>>>On September 30, 2004 at 18:19:01, Robert Hyatt wrote:
>>>
>>>>On September 29, 2004 at 19:54:50, Stuart Cracraft wrote:
>>>>
>>>>>On September 29, 2004 at 18:34:40, Uri Blass wrote:
>>>>>
>>>>>>On September 29, 2004 at 18:20:45, martin fierz wrote:
>>>>>>
>>>>>>>On September 29, 2004 at 16:21:43, Uri Blass wrote:
>>>>>>>
>>>>>>>
>>>>>>>>I think that it is clear that extending every nate threat by a full ply will
>>>>>>>>blow your search.
>>>>>>>>
>>>>>>>>If you do not use partial extensions then I suggest that you do not extend mate
>>>>>>>>threats unless  you have some conditions to extend them only near the root and
>>>>>>>>not every where.
>>>>>>>>
>>>>>>>>Uri
>>>>>>>
>>>>>>>i extend mate threat by a full ply always. and my search isn't blowing up, at
>>>>>>>least not that i notice. then again, WAC 141 shows some strange behavior with my
>>>>>>>latest version:
>>>>>>>
>>>>>>>MUSE 0.89.10 UCI 30 MB:
>>>>>>>
>>>>>>> 1   00:00 -1.65   Kg2g1
>>>>>>> 2+  00:00 -2.36   Kg2f1
>>>>>>> 2   00:00 -2.36   Kg2f1 Nf4d3
>>>>>>> 3   00:00 -1.22   Kg2f1 Re8b8 Kf1e1
>>>>>>> 4   00:00 -2.13   Kg2f1 Kg8h7 Bb3d1 Nf4d3
>>>>>>> 5   00:00 -2.16   Kg2f1 Re8e2 Kf1g1 Nf4d5 Kg1f1
>>>>>>> 6+  00:00 -1.66   Qc1xf4
>>>>>>> 6   01:24  M6  Qc1xf4 Bd6xf4 Rh4xh5 g6xh5 Rh1xh5 Bf4h6 Rh5xh6
>>>>>>>
>>>>>>>it sees Qxf4 after 0 seconds (this is on a slowly 1.4GHz P4), but needs a very
>>>>>>>long time to resolve it. but at least it sees Qxf4 in 0 seconds :-)
>>>>>>>
>>>>>>>cheers
>>>>>>>  martin
>>>>>>
>>>>>>If you extend also checks by  a full ply then there are cases when there is a
>>>>>>long sequence
>>>>>>check ,escape threat mate,check,escape threat mate and it means that you may
>>>>>>have big problems to search deep in position when one side threats mate but the
>>>>>>opponenthas a lot of checks because he tries to do perpetual checks.
>>>>>>
>>>>>>You can easily search some lines to more than 100 plies at small depth and  I do
>>>>>>not believe that it is a good idea.
>>>>>>
>>>>>>Uri
>>>>>>
>>>>>>
>>>>>>Uri
>>>>>
>>>>>This is very useful. Okay, in main search I can just start off with
>>>>>revaluing check extension to 0.75 instead of 1 but I'd expect that
>>>>>since I have few extensions, very few checks would be searched.
>>>>>How would you handle reducing check extension value in such an
>>>>>arrangement.
>>>>>
>>>>>Also, my quiescence search always investigates all check evasions
>>>>>to any depth. Should I be doing that?
>>>>
>>>>Absolutely not.  IE you capture at first q-search ply where you can also stand
>>>>pat.  Your opponent captures at the next ply and you try all moves to get out of
>>>>check and eventually find a deep mate.  It isn't forced as you can just stand
>>>>pat at the first capture and all that searching was wasted...
>>>
>>>The searching was not wasted unless standing pat is better because you learned
>>>that the capture is not good.
>>>Let take 2 examples
>>>
>>>[D]r5k1/6pp/4b3/7q/8/4R3/5PPP/N2B2K1 w - - 0 1
>>>
>>>If you search check evasion you can find that BxQ is bad and return the stand
>>>pat score that is bad for white.
>>>
>>>[D]r5k1/6pp/4b3/7p/8/4R3/5PPP/N2B2K1 w - - 0 1
>>>
>>>In this case of course you do not search after Bxh5 RxN+ because there is no
>>>check evasion to do the score above alpha and alpha in the beginning was the
>>>standpat score or something higher.
>>>
>>>Uri
>>
>>
>>I've said this hundreds of times...  I don't want my q-search to deal with that
>>at all.  Whether it does only captures or captures+checks+check evasions is
>>_still_ way too selective.  I can construct just as many positions where the
>>best move is not a capture or a check, and the q-search returns the wrong value.
>
>Yes but the question is simply if it plays better with check evasions or not.
>I want my qsearch to do everything that help my program to play better.
>
>Uri


I did checks/check-evasions in the q-search way back.  I took it out a few
months before the Jakarta WMCCC event as it played better in testing.  I've
never looked back...



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