Author: Robert Hyatt
Date: 10:20:29 07/23/02
Go up one level in this thread
On July 23, 2002 at 12:08:43, Uri Blass wrote: >On July 23, 2002 at 11:44:29, Robert Hyatt wrote: > >>On July 23, 2002 at 11:00:26, Uri Blass wrote: >> >>>On July 22, 2002 at 23:12:15, Robert Hyatt wrote: >>> >>>>On July 21, 2002 at 14:56:12, Robert Hyatt wrote: >>>> >>>>>On July 21, 2002 at 14:54:18, Robert Hyatt wrote: >>>>> >>>>>>On July 21, 2002 at 01:29:38, Uri Blass wrote: >>>>>> >>>>>>>On July 20, 2002 at 22:20:29, Robert Hyatt wrote: >>>>>>> >>>>>>>>On July 20, 2002 at 05:55:43, Uri Blass wrote: >>>>>>>> >>>>>>>>>On July 20, 2002 at 05:47:38, Gian-Carlo Pascutto wrote: >>>>>>>>> >>>>>>>>>>On July 20, 2002 at 02:52:11, Uri Blass wrote: >>>>>>>>>> >>>>>>>>>>>My question was not about comparing using hash tables >>>>>>>>>>>and not using hash tables but about comparing using hash tables >>>>>>>>>>>in the normal way and using hash tables >>>>>>>>>>>for all purposes except pruning. >>>>>>>>>> >>>>>>>>>>In the example given, the move ordering from hashtable is almost >>>>>>>>>>irrelevant, so all the gains are due to pruning. >>>>>>>>>> >>>>>>>>>>-- >>>>>>>>>>GCP >>>>>>>>> >>>>>>>>>I did not ask about single example from endgame but about >>>>>>>>>the middle game or about rating improvement. >>>>>>>>> >>>>>>>>>Uri >>>>>>>> >>>>>>>> >>>>>>>>I gave you an answer of sorts. Best case is fine 70. 3x as many plies. >>>>>>>>Middlegame seems to be a factor of 2x in terms of time to reaching a specific >>>>>>>>depth. So a fraction of a ply. So from early middlegame to endgame sees this >>>>>>>>go from a fraction of a ply to (say) 30 additional plies... >>>>>>>> >>>>>>>>The 30 is important. It doesn't just happen in fine 70. It happens in lots >>>>>>>>of important king and pawn endings. >>>>>>> >>>>>>>I know that in simple endgames you can get big improvement thanks to using hash >>>>>>>tables for pruning. >>>>>>> >>>>>>>I also know that you can get a factor of 2 in the middle game from hash tables >>>>>>>when the comparison is between using hash tables and not using them. >>>>>>> >>>>>>>It did not answer my questions. >>>>>>> >>>>>>>Only Christophe answered them when he explained that I may get 10% speed >>>>>>>improvement in the middle game from pruning. >>>>>>> >>>>>>>Uri >>>>>> >>>>>>OK... I will take my usual approach and simply give you _real_ data. >>>>>> >>>>>>Three positions. The first tactical, the second just a middlegame position >>>>>>with no real tactics, the last an endgame (fine70). All three searched with >>>>>>normal hashing, and then using hashing as normal, but not allowing the hash >>>>>>stuff to produce a fail high, fail low, or exact score. It can still tell me >>>>>>to avoid a null-move search. The difference in times, then, is _totally_ >>>>>>dependent on using the hash scores only, as everything else is identical. >>>>>> >>>>>> >>>>>> hashon hashoff >>>>>>Tactical 48 secs 78 secs >>>>>>normal 118 secs 183 secs >>>>>>fine 70 0 secs 58 secs >>>>>> >>>>>>In fine 70, both searched to 18 plies. hash on got right move (kb1 >>>>>>winning a pawn). hash off did not get right move. >>>>>> >>>>>>You can draw your own conclusions. 10% is obviously _way_ too low. I >>>>>>said roughly a factor of two, for middlegames, which is pretty close in >>>>>>the first two. In the last position we _know_ what hashing does. >>>>>> >>>>> >>>>> >>>>>I should add, if you _really_ don't think that I answered your question, then >>>>>maybe the question you actually _asked_ and the question you _meant_ to ask >>>>>are not the same thing. I believe my previous post shows that I _did_ >>>>>directly answer the question you asked. _exactly_... >>>> >>>> >>>>I find it interesting that I answer the question, get accused of not answering >>>>the question, then I post _real_ data showing that I answered the question, and >>>>the discussion stops cold... >>>> >>>>why would that be??? >>> >>>I thought that your data about being twice faster was about using big hash >>>tables against small hash tables and not about using hash tables for pruning >>>relative to using hash tables not for pruning. >> >> >>Think about it for a minute. If you use a tiny hash on a big search, what >>are you doing? Answer: Using _no_ hash. Using the "hash_move" is not a >>big winner to me in terms of tree size. What it lets me do is search faster >>because I can try this move first without generating anything, and if I get >>a cutoff, I get it with less work and go faster. If I disable the hash move, >>then killers and captures simply work better, and the overall difference is >>not very large. Except for the speed loss. >> >>If you use history moves for ordering, hashing is not going to be a huge >>win if all you get is move ordering from it. If you do pruning, then the >>question changes... > >I use hash moves only for ordering and it was clearly faster for me(about 1.5 >times faster). > >I use also history tables and 2 killer moves. Do you do hash move and killer moves _before_ generating legal moves? That is where I get the benefit. If just hash move is 1.5 times faster, I would suspect you are not doing killers right. IE getting captures into the killer list or something similar... > >I still do not use hash tables to save generating moves and it is another gain >that I can get from hash tables. and from killer moves. > >Uri
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