Author: blass uri
Date: 12:50:50 11/18/99
Go up one level in this thread
On November 18, 1999 at 14:52:20, Christophe Theron wrote: >On November 18, 1999 at 03:18:19, blass uri wrote: > >>On November 17, 1999 at 20:38:38, Thorsten Czub wrote: >> >>>On November 17, 1999 at 19:01:57, Christophe Theron wrote: >>> >>>>No Chris, you don't get it. If you prune too much on material criterias you >>>>completely destroy the positional skills of the program. >>> >>>Chris, ahem, or Bella , or whoever you are, and Christophe! >>> >>>Hi ! >>> >>> >>>I don't think tiger plays fast-chess. >>>it plays very nice chess. positional alike. >>> >>> >>>>If I wanted to go deeper tactically, I could do it easily. I think I could go 2 >>>>plies deeper. But in this case my program would be completely crushed because of >>>>incredible positional holes. >>>> >>>>Before the game goes on a tactical field, my program would have a totally lost >>>>position. >>> >>>>Each time I have tried to sacrifice the positional understanding to get deeper, >>>>it was a disaster. I have found that it works in the opposite direction: with >>>>better positional understanding the program goes deeper. Because it sees the >>>>right moves earlier, and spends less time analyzing sonense moves. >>> >>>Right. The more the program knows, the more it sees in the search. >>>Tiger has completely different evaluation than any other program >>>in most cases. >>> >>>If you want i can present lots of games and positions where tiger evaluates >>>DIFFERENT. often 2 or 3 pawns different than hiarcs/fritz/others. >>> >>>Why ? >>>Because it knows and comes also deeper. >>>And it seems it evaluates a special thing much higher than any other program. >>>i am sure i know what it is. but i will not say it. a secret so far. >>> >>> >>> >>>>You make it sound as if I had found a very specific way to shoot on a very >>>>specific weakness of a very specific subset of chess programs. >>>> >>>>You make it sound as if I was not programming chess. >>> >>>>You completely overlook the fact that several testers including our friend >>>>Thorsten have noticed that Chess Tiger has a large amplitude in its evaluation >>>>function. It's usual to see Tiger at +1.90 when the opponent is still close to >>>>0.00. >>> >>>Right. As i said :-))) it has a big evaluation function and very often has >>>completely different evaluation trend than the opponent. >>>and it wins. that makes it funny. >>>i like it because it is different. as chess system tal is. >> >>I do not think that the word bigger is right. >>It probably has a better evaluation function. >> >>The quality of the evaluation is relevant and not the size of the evaluation >>function. >> >>Uri > > >Quality and quantity in this case are related. If you have a lousy evaluation >function and do not trust it, you make it "small", that is for example always >returning values in the interval [-0.75;+0.75]. > >We all know many chess programs evaluating their position at -0.75 when they >have a dead lost position but material is still equal. > >These chess program would happily accept the lost position if they can capture a >pawn in exchange. > >With a "big" positional evaluation function, a program would never take the pawn >and save its position. > >So if you have a good positional evaluation function f(P) (that does not take >material into account), you can use f(P)/10 in your score or use f(P)*2. > >Both versions will play exactly the same moves in many positions. The difference >will be seen only when there is a choice like giving a pawn against a very good >position. In this case the "big" evaluation will coureagously accept the deal, >when the "small" evaluation version will stick to material balance only and play >boring. > >You see what I mean. With a given quality positional evaluation, it's possible >to play on the scale of this positional evaluation and the scale makes a >difference. > > > Christophe I understand now that thorsten probably meant by the word big to the value of the not material evaluation. The evaluation includes both the material scores and the positional scores and I did not understand that you define big evaluation function as evaluation when the positional score is relatively big. I thought that he meant by the word big to the number of commands you need to evaluate when slow searchers have a bigger evaluation by this definition. Uri
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