Author: Robert Hyatt
Date: 07:53:13 09/28/01
Go up one level in this thread
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. >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... > >I still believe that it is high enough in this case in order not to ponder on >the root move but it is possible that with more complicated conditions you can >find cases when the probability to ponder correctly is small enough so it is a >bad idea to ponder on the opponent's move. > >Uri
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