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

Author: Uri Blass

Date: 00:00:25 10/01/04

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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



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