Author: Stuart Cracraft
Date: 21:14:01 09/02/04
Go up one level in this thread
On September 02, 2004 at 21:21:41, Robert Hyatt wrote: >On September 02, 2004 at 16:44:58, Stuart Cracraft wrote: > >>On September 02, 2004 at 15:31:31, martin fierz wrote: >> >>>On September 02, 2004 at 09:45:25, Michael Henderson wrote: >>> >>>>On September 02, 2004 at 02:39:28, martin fierz wrote: >>>> >>>>>On September 01, 2004 at 10:11:18, Uri Blass wrote: >>>>> >>>>>>On September 01, 2004 at 05:57:25, martin fierz wrote: >>>>>> >>>>>>>On September 01, 2004 at 00:51:47, Stuart Cracraft wrote: >>>>>>> >>>>>>>[snip] >>>>>>> >>>>>>>Muse on P4 2.4GHz finds the mate at ply 6, failing high on Qxf4 after 0.7 >>>>>>>seconds (not shown in the logfile). >>>>>>> >>>>>>>the reason it can solve this at such a low search depth is probably twofold, the >>>>>>>first is that it generates checks in qsearch on the first ply of the qsearch (so >>>>>>>when you drop directly into qsearch with a nullmove, it will see Rh8# every >>>>>>>time), the second is probably that it is using mate-threat extensions. >>>>>>> >>>>>>>cheers >>>>>>> martin >>>>>> >>>>>>Do you get 2 plies only by mate extensions? >>>>>>In order to do it you need to extend 2/3 ply for mate threat. >>>>>> >>>>>>The line 1.Qxf4 Bxf4 2.Rxh5 gxh5 3.Rxh5 Bh6 4.Rxh6 is 7 plies and qsearch here >>>>>>does not see mate because it is black to move so I need 8 plies even if I >>>>>>disable pruning by evaluation. >>>>> >>>>>hi uri >>>>> >>>>>the reason must be that after 2.Rxh5 i get a mate threat extension and after >>>>>3.Rxh5 again, and since i do a full ply for that, my program sees it. >>>>> >>>>>cheers >>>>> martin >>>>> >>>>>> >>>>>>With pruning by evaluation latest movei get it only in 10 plies but I think to >>>>>>change my pruning to make it see it faster. >>>>>> >>>>>>Uri >>>> >>>>is recapture extension also playing a role here?...if that applies. >>> >>>it doesn't apply for me, but it probably depends on what an engine would >>>classify as a "recapture". some people might call any sequence of two captures >>>on the same square a recapture, for me a recapture is only if a piece of the >>>same value is recaptured. this isn't the case here. >>> >>>cheers >>> martin >> >>I consider a recapture to be a capture that restores the root material >>difference to what it was at ply = 0, before the search. >> >>Stuart > > >That is no good. The starting position comes right after I played BxN. It is >your move and you start the search. Material score is -3 for you. After you >make the re-capture at ply=1, I play RxR at ply=2. Score = -5. You play RxR to >make the score 0 again. 0 != -3 so you don't extend. Your example convinces. I discarded it and reclassify recapture extension as extend on 2nd capture on the same square. Didn't give a boost on the test suite though. Stuart
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