Author: Ricardo Gibert
Date: 19:15:31 07/19/02
Go up one level in this thread
On July 19, 2002 at 21:43:40, Robert Hyatt wrote: >On July 19, 2002 at 15:50:44, Uri Blass wrote: > >>On July 19, 2002 at 15:25:48, Christophe Theron wrote: >> >>>On July 18, 2002 at 12:14:10, Robert Hyatt wrote: >>> >>>>On July 18, 2002 at 05:58:56, Vincent Diepeveen wrote: >>>> >>>>>On July 17, 2002 at 13:18:40, Christophe Theron wrote: >>>>> >>>>>>On July 16, 2002 at 11:01:23, Vincent Diepeveen wrote: >>>>>> >>>>>>>On July 15, 2002 at 13:11:09, Christophe Theron wrote: >>>>>>> >>>>>>>>On July 15, 2002 at 08:37:34, Omid David wrote: >>>>>>>> >>>>>>>>>I don't think using double null-move is a good idea in practice, since in >>>>>>>>>midgame the chance of zugzwang is negligible and thus it's superfluous (I doubt >>>>>>>>>if even DIEP uses it). However the contribution of double null-move is that it >>>>>>>>>gives legitimacy to the null-move pruning idea, proving that it _is_ a correct >>>>>>>>>search method (anyway, no one doubts null-move nowadays). >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>>Why does double null move prove that null move is a correct search method???? >>>>>>>> >>>>>>>>Doing two null moves in a row means going back to standard search (a search not >>>>>>>>involving an illegal move like null move is). >>>>>>>> >>>>>>>>I fail to see how it legitimates null move. >>>>>>> >>>>>>>Double nullmove legitimates (duh can't you use easier to spell words) >>>>>>>itself, for the obvious reason that it is provable now that a search >>>>>>>depth of n ply, where i may pick n, is going to solve any problem you >>>>>>>give it. >>>>>> >>>>>> >>>>>> >>>>>>OK, I see now. >>>>>> >>>>>>However, it is not true. >>>>>> >>>>>>Due to a nasty interaction with the hash table algorithms, just allowing 2 null >>>>>>moves in a row will NOT solve any problem. >>>>> >>>>>What you refer to is a practical impossibility (assuming you have >>>>>a efficient search) : >>>>> >>>>> your assumption is that from a root position r >>>>> with transition of some moves to position p, side stm to move and >>>>> depthleft=d: >>>>> >>>>> r ==> p(stm,d) >>>>> >>>>> that you visit this position with properties that >>>>> before this move you have made 1 nullmove or less. >>>>> >>>>> so ==> r , nullmove , p >>>>> >>>>> Now a major problem for such an event to occur is that >>>>> after 1 nullmove, sides change the side to move. >>>> >>>>Why is this a problem? IE in my case, position P reached thru a path >>>>with a null-move and position P reached thru a path without null-move >>>>are _unique_ positions... >>> >>> >>> >>>If so, your programs loses a lot of opportunities to prune because it detects >>>less transpositions. But maybe it avoids some problems and is benefical in the >>>end, I do not know. >> >>How much do programs earn by pruning based on hash tables? >> >>Today I do not use hash tables to prune the tree. >>I am interested to know how much rating programs earn from >>using hash tables to prune the tree. >> >>1)Did someone do the experiment of comparing the rating of >>a chess program when hash tables are used only for things like order >>of moves and the rating of the same program when hash tables are used also for >>also to prune the tree. >> >>2)How much speed improvement do programs get in middle game >>from pruning based on hash tables? >> >>Uri > > >Try position fine 70 with and without. Without you might get to depth 15 >or so. With it you can reach depth 40. A _significant_ gain... You're trying to drive Uri crazy aren't you? Did you really think Uri could not think of an example of a position where having hash tables makes a significant difference? Do you really think being able to search a position like Fine 70 to a depth of 40 instead of 15 will make a difference in a programs playing strength? Don't you realize people are liable to react to such a reply as yours above as a troll? Please try to be a bit more thoughtful.
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