Author: Stuart Cracraft
Date: 13:44:58 09/02/04
Go up one level in this thread
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
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