Author: Uri Blass
Date: 13:14:14 05/28/02
Go up one level in this thread
On May 28, 2002 at 15:51:30, Robert Hyatt wrote: >On May 28, 2002 at 09:30:48, Sune Fischer wrote: > >>On May 28, 2002 at 09:09:18, Daniel Clausen wrote: >> >>>On May 28, 2002 at 04:05:47, Sune Fischer wrote: >>> >>>>I believe it is then safe to stop the search at 150 plies, that's 50 plies left >>>>for extensions(!), it will simply have to do, even if I get a crash in 1 of >>>>10000000 games ;) >>> >>>If you'd be in my programming team, either you or me would be looking for a new >>>job now. ;) A simple additional if-statement at the beginning of search makes >>>this 100% correct in all cases and slows down your engine by a _very_ small >>>factor. So basically you're just careless here - and therefore maybe also >>>careless in other places. ;) >>> >>>Remember that even though these small speedups do add up over time (and maybe >>>give you an additional +2 ELO boost in the next 10 years *grins*) the risk for >>>crashes or misbehaviours also adds up. And Murphy will make sure it will happen >>>during the most important game. =) [should it happen during a game against my >>>engine (in the future.. maybe..) I'll remind you of this thread =)] >>> >>>HTH :) >> >>"careless" :) >>Hmm, I don't know. I need to extend ~100 plies(!!) to get a crash for a total of >>200 plies search! >>Can you come up with any kind of position that would even slightly challenge >>this limit? To get many extensions you need checks or so, but then the position >>won't transpose as good (because it won't be blocked pawns), so really you need >>maybe 170 extensions in a 30 ply search, in all it's extremely unlikely. > >I got zapped by some "straightjacket" problems Harry Nelson used to work on. >The initial problem was to define a position where black and white had the >most consecutive forcing moves (one possible reply). I think Harry had one >that went 32 plies, which meant that in Cray Blitz, it extended 32+ plies >as well. And beyond that most of the remaining moves were forced for a while. >It blew our 64 move limit quite nicely (we had 64 because early crays had 64 >as a max vector limit due to hardware vector register size). If you do not have a condition of no repetition I can easily break that record. [D]5b1k/4p1p1/4PpP1/5P2/2p5/1pPp4/1P1P4/rKB5 w - - 0 1 Uri
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