Author: Torstein Hall
Date: 05:29:35 10/04/01
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On October 03, 2001 at 18:55:30, Uri Blass wrote: >On October 03, 2001 at 18:33:10, Torstein Hall wrote: > >>On October 03, 2001 at 17:59:14, Uri Blass wrote: >> >>>On October 03, 2001 at 16:51:49, Torstein Hall wrote: >>> >>>>On October 03, 2001 at 16:10:43, Robert Hyatt wrote: >>>> >>>>>On October 03, 2001 at 16:02:26, Torstein Hall wrote: >>>>> >>>>>>What if you run two paralelle search/chess processes. One going very fast with >>>>>>very little evaluation. The other going slow, with a big evaluation. The fast >>>>>>one always start searching on the move calculated by the slow process with the >>>>>>big evaluation, just checking for big materiall loss, tactical stupidities >>>>>>further down the tree. If it find one, the fast process sends a message goes >>>>>>back to the slow process and tells it do start work on the next best move. >>>>>> >>>>>>Then you perhaps can have the best from two "worlds". Intelligent search, with >>>>>>no tactical blunders! >>>>>> >>>>>>Torstein >>>>> >>>>> >>>>>Read Jonathan Schaeffer's reports on "Sun Phoenix". He did exactly that. >>>>>But he did it because he was not getting a very good distributed speedup >>>>>on larger numbers of processors. So some did a normal chess search together >>>>>as a group, the rest ran a tactical searcher called "minix". Minix was used >>>>>to refute moves chosen by the positional program. >>>>> >>>>>The problem is trying to rationalize the knowledgeable search vs the tactical >>>>>search. If the tactical search says your positional move loses material, what >>>>>do you do? Propose another move? And if _that_ loses material? The search >>>>>becomes hugely inefficient... >>>> >>>>If the tactical search says you lose material, of course you have to change the >>>>next best move, and so on. But that limit can perhaps be even more than a pawn? >>>>And of course if all the first moves in your oredering are very bad, it do not >>>>matter that much if you are not very effective. You are probably already >>>>loosing! >>>> >>>>Anyway, its another approach, and I find the consept intriguing. >>>>Can I find Jonathan Schaffer's report on Sun Phoenix on the net somewhere? >>>> >>>>Torstein >>> >>>I totally dislike the idea of using fast searchers for tactics. >>> >>>I believe that in theory a fast searcher should be worse in tactics because it >>>has no idea which lines to prune or extend and has no idea about the right order >>>of moves. >>> >>>It is possible to get more nodes per second by not using null move or extensions >>>and not calculating order of moves but the program is certainly going to have a >>>bigger branching factor and it is going to be weaker in tactics. >>> >>>My example is an extreme example but I believe that if you want an engine to be >>>better in tactics then doing it slower in nodes per second may be a good idea. >>> >>>Uri >> >>I for one do not have the time or ability to build a chess program, so I can not >>argue about, what teqnique to get deepest first. But the whole idea was to have >>a fast tactical deep searcher to correct a slow, big "evaluator". >> >>Torstein > >I believe that if you care only about tactics then it is better to have a slow >searcher and in this case adding a big evaluation is not going to be a big >problem. > >Adding a big evaluation is a big problem if you have a fast searcher and in this >case the program may be 10 times slower because of complex evaluation but if you >add big search rules before evaluation then the program may be only 2 times >slower thanks to the evaluation and adding the big evaluation is not a big >problem. > >Note that I also did not build a chess program(I built only a move generator to >calculate the number of legal games of fixed number of moves) and it is only my >intuition. > >Uri The idea was for a two processor system to have a fast tactical "checker" running in paralell with a slow large evaluator. If the fast tactical search finds a refutation, then you give a message to the slow big evaluator to change line. If this realy would work, is quite another question! :-) Torstein
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