Author: Robert Hyatt
Date: 18:21:41 09/02/04
Go up one level in this thread
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.
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.