Author: blass uri
Date: 12:07:07 04/07/99
Go up one level in this thread
On April 07, 1999 at 09:33:22, Tord Romstad wrote: >On April 07, 1999 at 02:39:10, blass uri wrote: > >> >>On April 07, 1999 at 00:59:33, Ted Sutton wrote: >> >>>Uri, >>> have you found positions where Junior5 finds the best move? >>> What sort of postion does that tend to be? >> >>I remember that there was one tactical position when Junior was the only program >>that could find kasparov's move against ivantuk. >> >>I cannot say that Junior is better at tactics and it is only about >>this specific position. >> >>Junior also found the best move in a study because it had a different evaluation >>function and evaluated the rook more relatively to the passed pawns. >> >>Fritz5.32 and Genius5 could not find the right move in the same position because >>they believed that the passed pawns are better than the rook. >> >>Junior can also find the best moves in some endgames because it gives endgames >>of KRN vs KR or KRB vs KR evaluation that is not a big advanatge for the better >>side. >> >>Junior can find better move than Fritz sometimes because Junior is not a stupid >>root processor like Fritz. >> >>Fritz can trade queens and understand only after trading queens that it was a >>bad idea and not because it sees more plies. >> >>Something like this cannot happen to Junior. > >I am not sure about this --- I very much doubt that Junior is doing a full >eval at the leaves (it is simply too fast for this). My guess is that Junior >uses some kind of hybrid approach. A preprocessor is probably applied >somewhere _within_ the three. When Junior does an n-ply search, I believe >that the preprocessor is applied at all positions of depth n-d (for some small >value of d) and that the eval is updated incrementally for the last d plies >(plus extensions). This is certainly a very oversimplified explanation of >what Junior does (just thinking about all problems this would give in the >implementation of hash tables gives me headache, for instance), but I don't >think I am missing the mark completely. > >If I am right in my above speculations, the problem you describe in Fritz >will sometimes also occur in Junior, but of course not nearly as often. You are probably right in your speculation but the problem with fritz is that it never can see the result of trading queens and it is not a problem of depth When I said that something like this cannot happen to Junior I meant to the problem of never seeing the right evaluation of trading queens. Junior can see the results of trading queens. If it trades queens at depth n-d then it will see the right evaluation at depth n so the problem of never seeing... cannot occur in Junior. Uri
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