Author: Uri Blass
Date: 00:00:25 10/01/04
Go up one level in this thread
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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