Author: Eelco de Groot
Date: 13:05:35 08/09/99
Go up one level in this thread
Thanks for trying that out, Paulo! That would be just about what you would expect, I suppose, if it follows the rule of thumb Robert Hyatt posted the other day; that the best move takes up about half the time of a normal search and that for n-best search for n>1 you can expect to have to add n-1 times that amount. In this case with n=6 it would be more or less 5X150=750 seconds to add to 300. But the key move wasn't found (I certainly do hope it was somewhere near the first six?) so this can mean for 'really difficult' positions you have to search at least one ply deeper to get the same level of accuracy in determining the best move. Not really a problem if you are doing an overnight analysis unless somewhere along the way you're running out of hashspace... I suppose it does happen sometimes, even for those of us with 192 MB :-). Then the search slows down to a crawl. With n=6 the hash tables get full almost six times sooner too or am I wrong? I suspect Hiarcs already limits the extensions to try to postpone that, it would be my explanation why you didn't find d5. This is probably (just guessing) one of the reasons why Ed hasn't implemented n-best search yet, to do it really well you'd have to find (n-times) better algorithms and replacement schemes for not letting the hashtables run over, at least for n-best overnight analysis. And especially for customers who have some difficulty saying goodbye to their old machines that is the only way to go 'really' deep. I'm not saying I myself wouldn't like such an n-best feature though, but possibly to use it the way I think you are using it and for which Steve uses Analysis Exclude, to get an indication which moves are plausible. I would only use it for deep searches if I could run it comfortably in the back ground for a couple of days. You can't use a lot of hash, but that would be full quickly anyway. I'm not too fond of using Analysis Exclude for deeper searches either, it means duplicating a lot of the search each time? I know, only half of the time was spent on these moves in the last search, but that is still a lot of information you would be duplicating then. If you do one Analysis Exclude every night, when you are not using the computer for anything else, you get accurate results too but it still does seem inefficient. So what conclusion to draw? I think it is best to always start with a 'normal' search and for that I'd really like the Overnight Search which is to come with Rebel Century. Claudio Bollini's diagram of its efficiency was very impressive. Thanks for the reviews, Roy, Claudio! The examples help a lot. I hope we can expect some more? After this first search the best way to go forward still has to be invented I think. I'd prefer to do a normal search and if there are other moves that look plausible I'd rather carry them out on the board and start another search, now one ply deeper. Luckily Rebel doesn't have too much asymmetry in its evaluations, so after reversing the sign you have a good indication. And if I'm not using Rebel ECTool I can make use of Analysis Include with one move to include, so there should be no asymmetry at all. It is more risky this way (Analysing not using Analysis Exclude I mean), but you have to make a choice which moves to look at somewhere along the way anyhow. Still this approach is not the best one possible because the computer has already generated a lot of information about these moves in its first search. You are not using any of it in this way. There must be better approaches... Does anybody think some form of temporary position learning could be used here? My idea would be to have a separate register for each of what I call the non-principal rootmoves, in which to store just the deeper evaluations that arise after this move. Everything can be thrown away after leaving Analysis Mode. Regarding Rebel, I think it would really be already a useful help if, at the end of a search, using Rebel's warroom, the last warroom variations could also be written to the logfile. And it would be even more wonderful if there were alpha-beta scores for these moves... Regards,Eelco. On August 08, 1999 at 10:33:55, Paulo Soares wrote: >On August 07, 1999 at 17:04:31, Eelco de Groot wrote: > >>Paolo, I believe you are not the first to ask for this kind of feature :-). >>Maybe this would mean a major rewrite of Rebel's engine or even a totally >>separate N-best Engine? As it is written in assembly language, this would be a >>tough job. Maybe if you ask Christophe very nicely one day....(ChessTiger is >>written in C). Actually I have never tried this kind of feature, isn't it very >>slow? >> >>Regards,Eelco. >> >>On August 07, 1999 at 08:49:47, Paulo Soares wrote: >> >>>On August 07, 1999 at 04:19:48, Tina Long wrote: >>> >>>>On August 06, 1999 at 12:39:15, Paulo Soares wrote: >>>> >>>>>Whithout doubt: Hiarcs7.32 >>>>> >>>>>Paulo Soares >>>> >>>>I agree, >>>>The Fritz GUI allows: excellent "Correspondence Analysis", printable gamefile >>>>with annotations, backwards with English (verbous) game analysis, good editable >>>>book, great database features, etc etc. >>>> >>>>Hiarcs is currently the smartest engine for the CBase family, Fritz is much >>>>faster & deeper. The slowsmart vs fastdeep is roughly equivalent at Tournament >>>>time, but (I feel) Hiarcs does better for long time analysis. >>>> >>>>Chessbase 7 does all this & a whole lot more, but is extremely expensive >>>>compared to F5.32 or H7.32 >>>> >>>>Meanwhile Rebel Century may be worth waiting for. Ed says it's got a special >>>>"overnight" analysis level. >>>> >>>>Hi guys, >>>>Tina Long >>> >>>Tina, Rebel is a great program for analysis too, but I feel lack of >>>the "Infinite Analyses" feature (N moves). I like to analyze positions >>>looking at some moves, with its variants and evaluations. When Ed >>>goes to put this feature in Rebel? >>> >>>Paulo Soares > >Eelco, I never had made a comparison between "normal" mode and "infinite >analyses" mode. I was curious and I made the following experience: > >1. System: PII 300, RAM=192Mb, OS WIN98. > >2. Program: Hiarcs7.32, HT=64Mb, Position Learning=OFF, Playng Style=Normal, > Selectivity=5, Contempy Value=15, Tablebase=OFF. > >3. Position: LCTII, Pos14, key move= d5. > FEN "r2qkb1r/1b3ppp/p3pn2/1p6/1n1P4/1BN2N2/PP2QPPP/R1BR2K1 w kq 0 2", > >4. Time to finish depth 9: > 4.1. Normal: 309"(5min 09sec) > 4.2. Infinite Analyses(N=6): 1000"(16min 40sec) > >5. Move chosen in the end of depth 9: > 5.1. Normal: d5 (Evaluation= +0.55) > 5.2. Infinite Analyses(N=6): a4 (Evaluation= +0.41) > > >Obs: I initiated each test after to give a boot in the machine. > >In the experience that I made the "Infinite Analyses" mode it's really >very slow, and the key move, d5, it was not found. >Independent of the result of that experience, I like to analize >positions using the "Infinite Analyses" mode, forcing the program >to make a move, with satisfactory results. > >Paulo Soares
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