Author: Sune Fischer
Date: 07:00:44 01/26/02
Go up one level in this thread
On January 26, 2002 at 09:50:17, Uri Blass wrote: >On January 26, 2002 at 09:32:43, Albert Silver wrote: > >>On January 26, 2002 at 09:27:03, Sune Fischer wrote: >> >>>On January 26, 2002 at 09:07:51, Albert Silver wrote: >>> >>>>>>>Realisticly a 2800 player probably has a branchfactor of no more than 2, ie. he >>>>>>>is able to always choose the best or second best move (on average). >>>>>>>If the average game lasts 100 moves, then that is still 10^30 plausible games of >>>>>>>which only a handfull will be good enough against *perfect* play. >>>>>>>Poor odds I agree with you :) >>>>>> >>>>>>You're presuming that anything other than one move, the best move, will lose >>>>>>forcibly to best play. I believe that more than one move is available to a >>>>>>non-loss thus perfect play would be often a flip of the coin between a few >>>>>>(perhaps three as I hypothesized in another post in the thread) moves. I have >>>>>>seen no evidence to suggest there is only one path to a non-loss and that a >>>>>>single path of perfect play is needed to avoid it. Everything we know whether >>>>>>from personal research or from the current tablebases suggests there are several >>>>>>paths. If this were accepted to be true, the question would be whether the 2800 >>>>>>player is incapable of hitting on _one_ of these non-losing moves (according to >>>>>>perfect play). >>>>>> >>>>>> Albert >>>>> >>>>>You could interpet in an similar way; there is a 50% chance of the 2800 chooses >>>>>a move that is *good enough*. >>>>>It was just an estimate, probably way off :) >>>>> >>>>>Suppose that a *correct* move is done with 95% certainty (on average) and that >>>>>the average game length is only 60 moves, then he has a 0.95^60 = 4.6% chance of >>>>>a draw! >>>>> >>>>>This is perhaps more realistic? >>>>> >>>>>-S. >>>> >>>>Well, a few things come to mind. One is that there would be more than one >>>>correct move to hit on. >>> >>>Yes, and that why I rephrased it to be a *correct* move rather than *the best* >>>move, by *correct* I mean a move that isn't losing. >>> >>> >>>>Second that I wasn't aware that his chances changed with >>>>each move, so I don't think that the longer the game the worse his chances. Give >>>>a 2800 player a dead equal dry game and I don't think he will suddenly be in >>>>danger of losing just because it can take 40 moves to trade off the pieces and >>>>pawns and play the endgame to the end. There is more to chess than probability. >>>> >>>> Albert >>> >>>What I meant was, that at every move he has a 5% chance of _not choosing the >>>correct move_, ie. he "blunders" by playing inaccurate. >>>That is an average percentile taken out of the blue of cause, but the tablebase >>>test could give us a hint whether we are talking 95% or 50%, it would allow us >>>to calculate the rating of a perfect player, which was the goal I believe. >>> >>>-S. >> >>I was addressing two things: Dann's statement that against perfect play, >>Kasparov (or any other 2800 player) would lose 1000 games in 1000. And your >>statement that against perfect play in a game of say 60 moves he only had a 4.6% >>chance of surviving. I think both statements are completely unreal and show >>little understanding of certain realities of both chess and their ability. You >>could also take a dead equal rook endgame where there is no chance for the >>mighty player to calculate a line to the very end and I would still adamantly >>state that his chances of losing are _zero_ and not some percentage that grows >>exponentially with each move played. >> >> Albert > >I agree Well I don't, I don't see what there is to object to, I specificly said they where estimates and averages. Albert talks about a dead drawn endgame with rooks that is easy to hold, then yes in _that case_ the factor goes to 1.00. But that is only one single case and why would the perfect player choose to end up in such a position? >The probabilities are not independent numbers. True, I also never said that, I only said average. >The probability can go down from 5% to 0% and can go up from 5% to 20%. I agree, they most probably will, some endgames are dead draw and in some tactical middelgame positions it is very easy to blunder, even for a super GM. >The probability may be 95% to be right for every move but more than 0.95^n to be >right in n moves when the events are not independent. I'm not sure what you mean? -S. >Uri > >Uri
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