Author: Tony Werten
Date: 23:43:54 10/05/01
Go up one level in this thread
On October 05, 2001 at 02:28:59, Dann Corbit wrote: >On October 05, 2001 at 02:10:32, Christophe Theron wrote: >[snip] >>Yes it's the classical explanation of this theory of "search vs knowledge", but >>as far as I know you do not need an enormous k2 and k3 to get the best branching >>factor that can be achieved nowadays. >> >>And if you have a huge k2, I can predict that your program is going to be >>criticized for being a root processor! :) >> >>It might happen some day that we find some expensive way of achieving better >>branching factors, but at this time we do not need to slow down the nps rate >>(even in a very fast searcher) in order to get state-of-the-art branching >>factors. > >How do you know that Stefan Meyer-Kahlen has not achieved this in Shredder (IOW: >maybe he _has_ achieved a branching factor better than anyone else by ludicrous >gobs of knowledge). > >>I would also like to point out that if you find some extremely expensive way of >>getting a better branching factor, you can keep your nps very high and still get >>the benefits of your better BF by applying your system on the first plies only >>and letting the last plies running at full speed. You do not have to have a run >>time of k2+k3*exp(k4*depth). >> >>Further, the formula has nothing to do with my idea of dimishing returns from >>knowledge (exactly like dimishing returns from search depth), which was what I >>was trying to stress out. > >Actually, I think I did understand you. All chess programs are going to "hit >the wall" because of the exponential nature of chess. Once you get to (for >instance) 17 plies in ten minutes, ply 18 is going to be hecka-hard (maybe >taking days). > >But a smaller branching factor (of say 20%) can accomplish something phenomenal >in that regard. Sort of like what NULL move accomplished. Shave the tree way >down so you only search the fat branches and suddenly you're zooming. Of >course, it's *still* an exponenatial search. But I would hate to compete with >someone who did trim the tree and I achieved no trimming at all. Pure >alpha-beta will get slaughtered by a null-move alpha beta. If a similar >reduction is gained through other means [e.g. I believe that Rebel does not use >null-move but achieves the reduction in other ways] then you will have to be >millions of times faster to achieve the same depth. Rebel Maastricht ( the latest version ) uses nullmove. Tony > >Reducing the branching factor is where it's at. As soon as we reduce it to 1, >chess will be solved.[1] >;-) > >[1] Assuming that the trimming is perfectly accurate.
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