Computer Chess Club Archives




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

Author: Robert Hyatt

Date: 15:19:01 09/30/04

Go up one level in this thread

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.
>>>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 :-)
>>>  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.
>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
>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...


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