Author: Uri Blass
Date: 09:34:11 09/28/01
Go up one level in this thread
On September 28, 2001 at 10:53:13, Robert Hyatt wrote: >On September 28, 2001 at 02:09:11, Uri Blass wrote: > >>On September 27, 2001 at 23:42:31, Robert Hyatt wrote: >> >>>On September 27, 2001 at 17:48:32, Peter Fendrich wrote: >>> >>>>On September 27, 2001 at 15:12:43, Roy Eassa wrote: >>>> >>>>>On September 27, 2001 at 12:13:10, Peter Fendrich wrote: >>>>> >>>>>>On September 26, 2001 at 21:45:46, Robert Hyatt wrote: >>>>>> >>>>>>>On September 26, 2001 at 20:32:58, Dann Corbit wrote: >>>>>>> >>>>>>-- snip -- >>>>>> >>>>>>>If you correctly predict your opponent's move at least 50% of the time, or >>>>>>>more, then the way we currently ponder can _not_ be improved on. >>>>>> >>>>>>I don't agree if that's what you really mean. "can _not_ be..." is hard to prove >>>>>>in this case. In theory at least you can do better. The _average_ hit rate is >>>>>>>50% >>>>>>If you know that this hit rate vary with different circumstances you will find >>>>>>out different hit rates. If we could separate out cases with very low hit rate >>>>>>it might be succesful with another scheme for just these cases. I've never >>>>>>tested this but it would be interesting to see the hit rate for "consistent" >>>>>>FH's (survives several iterations) compared to the rest. The hit rate for >>>>>>pondermoves giving about the same evaluation as before is probably higher (much >>>>>>higher?). >>>>>>I can think of other types of cases as well. >>>>>>Has anyone computed the figures for different cases like this? >>>>>> >>>>>>I would like leave this "can _not_ be..." open until at least some test like >>>>>>this is done. >>>>>> >>>>> >>>>> >>>>>The factor that causes the engine to be unsure of the move it selected to >>>>>ponder, is the SAME factor that makes pondering multiple moves less useful. >>>>> >>>>>If there are several moves that are all about equal, then there are, by >>>>>definition, also several moves among which you must divide your time pondering. >>>>>Thus even if you were only 20% sure of your opponent's move, it still does not >>>>>make sense to split your pondering time because each likely move would then get >>>>>no more than that same 20%. >>>> >>>>Yes, I buy all that. My intention was to oppose to the "it's impossible" >>>>statement. You are talking about some general case. There is no reason why each >>>>move has to be 20% because the first one is. That's why I'm talking about >>>>isolating cases where the other move might be better. Another question is what >>>>happens if the ponder move has only 10% or 5% probability. >>>>I have no proofs that these cases are possible to identify but I'm still open >>>>for it, until I know better... >>>>//Peter >>> >>> >>> >>>The question is, what would cause that 10%. IE this is all speculation since >>>we won't know whether the opponent will match or not, until he makes a move... >>> >>>But based on collected statistics, Crafty _always_ predicts at well over 50% >>>accuracy. And as long as that is possible, I don't see any way possible to >>>better utilize pondering time. Because it will _always_ be right over 50% of >>>the time and save that time. >>> >>>Here is a test scenario: >>> >>>1. Assume my opponent _never_ predicts my moves correctly. IE crafty is the >>>only one that ever predicts a move. In this case, crafty is the _only_ player >>>that will save any time pondering. >>> >>>2. Assume Crafty predicts correctly 60% of the time, and the game being played >>>is such that it has one minute per move, fixed, to make it simple. Then it >>>will average saving 36 seconds per move over the game, based on that 60% >>>prediction rate (.60 * 60 seconds). >>> >>>Now, given those two constraints, give me an algorithm that will save more >>>than 36 seconds per move, on average... You can assume anything you want, >>>just so you don't violate the 60% prediction rate already given. >> >>No problem >> >>Suppose that you have an algorithm to tell you in 10% of the cases that the >>probability to ponder correctly is only 1%(I do not know about an algorithm to >>do it but it does not mean that there is no algorthm to do it) >> > > >That won't fly. No "oracles" allowed here. I want a _specific_ algorithm >that will beat that 60%. If I have an oracle then I can predict right 100% >of the time. That is a circular argument. If you know in 10% of the cases that your prediction is probably wrong it does not mean that you can predict right in 100% of the time but only that you can predict better than 60% in this case even choosing another random move to ponder in the 10% of the cases(assuming that there are less than 100 legal move) may be a better strategy than pondering on the expected move. > > > >>It does not violate the 60% prediction rate because you may have probability of >>almost 70% to predict the corect move in the rest of the cases. >>In this case it may be better to ponder the root move in 10% of the cases. >> >> >>I think that you can evaluate the probability that you ponder correctly based >>on the move that you ponder better. >> >>For example I guess that the prediction rate when you predict waste tempo move >>is smaller than the normal probability but I do not think it is something near >>1%. >> >>If the last move was Ra1-b1 and crafty ponders on Rb1-a1 or Rb1-c1 then I guess >>that the prediction rate is lower than the normal prediction rate. > > >Not against computers, for one counter-example... Do you have statistics that it is not against computers? It is possible that the computer opponent has a different evaluation function than crafty and the plan push it to play for an attack when Crafty expects it to play for a repetition. I think that using the history in the specific game may be also productive Example:Suppose crafty failed to ponder correctly in 7 out of the last 10 moves when the evaluation from Crafty's point of view often starts from a positive number and goes down to 0.00 in these moves In this case you may suspect that the opponent has a different evaluation and if Crafty expects a repetition line you may suspect that the opponent has a different evaluation and is not going to play for a repetition line. Improving the pondering is not simple and I do not say that you can get a lot of improvement but I do not think that it is right to assume that it is impossible without investigation of it. I can understand if you say that you do not want to waste time for an estimated improvement of 1-2 elo that you may earn. Uri
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