Author: Uri Blass
Date: 15:20:42 09/28/05
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On September 28, 2005 at 17:54:13, Robert Hyatt wrote: >On September 28, 2005 at 14:38:39, K. Burcham wrote: > >> >> >>Do you know of a position in the Deep Blue vs Kasparov games, that todays >>programs cannot find? I am trying to find a position that not even one program >>today can find this position without very long search. I will conclude that this >>position cannot be found with default knowledge. I am looking for a position >>that I can see that no program of today, with default settings will find this >>Deep Blue game position without leaving one of my programs running for a very >>deep search. >> >>kburcham > > >I am almost certain that, by definition, such a move is not going to be found. >Because many moves (both good and bad ones) are made for the wrong reasons. And >most likely, unless we find some wild tactical position that simply confuses >current searches completely, but DB was able to work thru it, then most any >other kind of position is not going to be useful. > >For example, how many times have we seen problem positions where it is "white to >play move XXX and win". And one (or more) programs play move XXX with a + >score, that is convincing. And one (or more) programs play move XXX with a - >score, which means it is playing the right move for the wrong reasons. Ditto >for programs that also play move XXX with a score of 0.0 thinking it is the only >way to avoid a loss, when it is the right way to actually win. Most positions, >other than those ending in mate, or with huge material wins, rely on both search >and evaluation. And a program that is a bit top-heavy on king safety might find >more of Tal's favorite moves than a program with a more conservative >(Karpov-like) evaluation. Yet both are equally strong overall. > >Finding these kinds of positions is _very_ difficult, because there are so few >DB 2 (last match) games available. In fact, I only know of 6. Which limits the >number of total positions available to a very small set. The likelihood of >finding such a position in that small set is _very_ small to say the least. For >example, many criticized the h5 move by DB in either game one or two (I don't >remember and don't have the logs handy). Kasparov said "that was the only move >to play". Later he questioned the move as being un-computer-like, until someone >pointed out that some version of Deep Junior would play the same move. So as >you can see, finding a bad move by DB that other programs avoid, is just as hard >as finding a good move by DB that other programs can't find. I think that finding a bad move by DB that other programs avoid is not so hard and I remember that I tested it some time ago and all the programs that I tried could avoid Kf1 in game 2 after some minutes. You may say that they avoid it not for the right reason because they do not see the draw but the fact is that they avoid a bad move of DB. Note that programs can see Qe3 in the pv before finding that Kf1 is bad when DB could not see it. It tells me that one of the following is correct in the relevant position: 1)programs of today saw deeper than deeper blue so they can see that Qe3 is not so bad as DB evaluated. 2)programs have better evaluation than deep blue in the relevant position. Uri
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