Author: Uri Blass
Date: 07:04:07 10/04/01
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On October 04, 2001 at 08:29:35, Torstein Hall wrote: >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 I understood the idea. My point is that a slow searcher should not be significantly slower in tactics by big evaluatoion when it has a big search rules. If the big evaluation does not do the slow searcher significantly slower in seeing tactics then the best idea is simply to use the slow searchers. There are examples that prove that slow searchers are not always weaker in tactics and I see no reason to assume that they should be weaker in tactics than fast searchers. Chest is the best mate prover and it is rekatively a slow searcher. Chessmaster is the best mate finder and it is relatively a slow searcher. Uri
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