Author: Tony Werten
Date: 00:29:51 03/30/01
Go up one level in this thread
On March 29, 2001 at 22:38:33, Christophe Theron wrote: >On March 29, 2001 at 16:01:51, Tony Werten wrote: > >>On March 29, 2001 at 15:12:21, Christophe Theron wrote: >> >>>On March 29, 2001 at 14:39:34, Tony Werten wrote: >>> >>>>On March 29, 2001 at 14:21:16, Christophe Theron wrote: >>>> >>>>>On March 29, 2001 at 13:49:06, Tony Werten wrote: >>>>> >>>>>>On March 29, 2001 at 13:31:59, Christophe Theron wrote: >>>>>> >>>>>>>On March 29, 2001 at 09:14:57, Robert Hyatt wrote: >>>>>>> >>>>>>>>On March 29, 2001 at 06:22:13, Jouni Uski wrote: >>>>>>>> >>>>>>>>>On March 29, 2001 at 06:17:50, Alexander Kure wrote: >>>>>>>>> >>>>>>>>>>On March 29, 2001 at 04:37:19, Tony Werten wrote: >>>>>>>>>> >>>>>>>>>>>Hi all, >>>>>>>>>>> >>>>>>>>>>>until what depth do various programs probe the tablebases ? >>>>>>>>>>> >>>>>>>>>>>cheers, >>>>>>>>>>> >>>>>>>>>>>Tony >>>>>>>>>> >>>>>>>>>> >>>>>>>>>>Hi Tony, >>>>>>>>>> >>>>>>>>>>In London 2000, I let Nimzo 8 play with a depth of 6 plies, but later I came to >>>>>>>>>>the conclusion that 8 plies might be better overall. This is indeed the default >>>>>>>>>>setting of NimzoX and Varguz playing on ICC. >>>>>>>>>> >>>>>>>>>>Greetings >>>>>>>>>>Alex >>>>>>>>> >>>>>>>>>Sorry one stupid question: is this the first or last 6/8 plys? >>>>>>>>> >>>>>>>>>Jouni >>>>>>>> >>>>>>>> >>>>>>>>His statement would make no sense if it were the _last_ 6-8 plies. Those >>>>>>>>are the ones that kill performance if you aren't careful. The first 6-8 plies >>>>>>>>don't cost a thing. >>>>>>> >>>>>>> >>>>>>> >>>>>>>But it could also mean it probes TBs in all the plies except the last 6/8. >>>>>>> >>>>>>>Meaning that if Nimzo is doing a X plies search, then the program probes the TBs >>>>>>>in the tree for all nodes that have a distance from the root below or equal to >>>>>>>X-6 (or X-8). >>>>>> >>>>>>Could be but that would mean, with an average depth of 10 to 12, you'd be >>>>>>probing the first 4 to 6 ply. I mean, it helps but it could help more. >>>>>> >>>>>>That is, not counting extensions, but you if you search 10 ply, you don't know ( >>>>>>at ply 8 ) how many plies are still coming. >>>>>> >>>>>>cheers, >>>>>> >>>>>>Tony >>>>> >>>>> >>>>>But you know how many plies you have done since the root position... >>>> >>>>2 possibilities: >>>>- We are talking about different things >>>>- I don't get it >>>> >>>>Might be both. >>>> >>>>Tony >>> >>> >>>You don't know how many extensions you are going to do, so you just ignore >>>extensions and assume you are going to search full width the same number of >>>plies as your iteration number. >>> >>>So at iteration 10, stop probing TBs after two moves from the root (assuming >>>like Nimzo that you don't probe in the last 8 plies of search). >>> >>>That is why I say "you know how many plies you have done since the root >>>position...". >> >>But then you don't have almost no depths where you probe. (In your example only >>ply 1 and 2 ) > > > >Yes, but your NPS does not go too low then. > >It's a compromise between speed of search and accuracy of the evaluation. > >Don't forget that accessing a TB slot can be as expensive as searching 1000 >nodes (depends on your program). And that many TB accesses are just a waste of >time because they are not going to have any influence on your main line. > >I'm not saying that 8 plies like in Nimzo is the right number (actually I'm not >even sure that Nimzo does it this way). > >In Tiger I stop accessing the tablebases a few plies before I reach the horizon. >If I don't do that the program gets much weaker because of the dramatically >slower NPS. Make your program slower ! XiniX is a slow searcher and I'm testing on slow hardware so I hardly notice a slowdown because of probing. ( Might not be the best solution ) The idea I have for probing a lot is that if a position is worth being searched, it's probably worth being probed. ( Unless you're very near to the leafs ) Hmm, search position normal, then store no nodes in hashtable, then when searched second time: if n.o. nodes>1000 do probe. I'll have a try. Maybe combined with: first x ply always probe. Positions below current position stored in hashtable can help with enhanced transposition cutoffs as well. I'll put it in my totry book. Tony > > > > Christophe
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