Author: Robert Hyatt
Date: 20:08:16 07/19/02
Go up one level in this thread
On July 19, 2002 at 22:15:31, Ricardo Gibert wrote: >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. There was _no_ troll involved. Point by point. fine 70 _is_ an important hash test. It represents a near-best-case for hashing. Which is the best you can do. It increases the search depth by at least a factor of 3x in terms of plies searched. Will that help the program? Clearly in king and pawn endings I see 20+ ply searches _all_ the time. And _that_ definitely helps for those positions where K+P endings are reached. But if you want to take a middlegame position, hashing is worth at least a factor of 2x based on tests I have run in the past. I can always run them again. So to summarize, fine 70 was and is legitimate. It _clearly_ shows that hashing makes a significant difference. I hardly see why _your_ post wouldn't be considered a "troll" in fact. As it attacks a legitimate point in a utterly simplistic and wrong context... Perhaps you should follow your own advice and try to be more thoughtful. _prior_ to posting???
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