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

Author: Stuart Cracraft

Date: 16:58:54 09/29/04

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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?
>
>Stuart

The only thing I can think of is to keep an Extensions[Ply]
and see, at ply, if Extensions[Ply-1]+Extensions[Ply], is > 1
and if so then to extend, unless Extensions[Ply-1]>1 in which
case only extend if Extensions[Ply]>1 also. Then also to
start with check extension revalued to 0.75. But since I can't
visualize whether this would work for the tree, I haven't
tried. I need to just plug it in and see what happens.

Stuart



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