Author: Vincent Diepeveen
Date: 19:56:40 11/21/02
Go up one level in this thread
On November 21, 2002 at 21:39:06, Uri Blass wrote: >On November 21, 2002 at 21:21:09, Vincent Diepeveen wrote: > >>On November 20, 2002 at 17:51:40, Alessandro Damiani wrote: >> >>'verified' nullmove, or in a different implementation but >>same algoritm, with just 1 ply reduction is nearly a fullwidth >>search. >> >>I did with a bigger reduction of course. that's also very >>costly compared to R=3. This was just an experiment carried >>out years ago when it was described in ICCA journal. Now >>we have same algoritm in a few lines diff algorithm. >> >>I do not see how Omid can just suffer 50% slowdown of his >>algorithm. Note he only publishes search depths not >>search times. That is wrong. >> >>You must publish search times. > >I do not see how you can suffer more than 50% slow down. Of course you suffer more than 50% slowdown. Every person with a decent chessprogram will suffer more than 50% slowdown. This is trivial. >I think that you simply do not understand the algorithm. I understand it perfectly well. I have run with it for years. So please apologize to me! >The algorithm does not do nearly full width search because after the first >reduction the search is normal null move pruning without verification. Yes it nearly does, it is a reduction of just 1 ply! With nullmove you reduce in the same subtree 4 ply. Or with R=2 you reduce 3 ply! Do you understand that with a branching factor of 3.5 that a search depth of 2 ply more means about a factor of 10 times more nodes more or less and not factor 2? >It did not work for movei or for sjeng but the difference is not as big as you >describe and I suspect that with some modification it may work. > >Uri >> >>I suffer plies if i reduce just 1 ply. >> >>R=2 or R=3 is irrelevant to that. >> >> >> >>>> >>>>One final remark: You use standard R = 3 in DIEP. So the search tree constructed >>>>by your program will definitely be smaller than that of verified R = 3. Many >>>>people find standard R = 3 as too risky; but if you are happy with its overall >>>>tactical strength, then I don't recommend you to shift to another method. But >>>>for those who'd like to get greater tactical strength than standard R = 2, and a >>>>smaller search tree than R = 2, I recommend to try verified null-move pruning. >>>> >>>>Best, >>>> >>>>Omid. >>>> >>> >>>Vincent uses R = 3 and complex quiescence search (Vincent, correct me if I am >>>wrong). Maybe your Verified Null-Move gives about the same results like R = 3 >>>with a complex quiescence search. >>> >>>_If_ this is true then your approach is simpler and therefore better. Just my >>>two thoughts before going to bed. Good nights....... >>> >>>Alessandro
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