Author: Stuart Cracraft
Date: 14:08:05 12/20/05
Go up one level in this thread
On December 20, 2005 at 00:19:22, Vincent Diepeveen wrote: >On December 16, 2005 at 03:32:16, Vasik Rajlich wrote: > >>On December 16, 2005 at 00:56:04, Zappa wrote: >> >>>On December 15, 2005 at 17:05:00, Sergei S. Markoff wrote: >>> >>>>1) Fruit. >>>> >>>>Fruit search seems to be primitive. "History pruning" is a variation of >>>>well-known idea. After implementing such method in SmarThink some years ago I >>>>named it "history-based pruning" and then changed to "ordering-based pruning". >>>>The outcome of such methods very depends of whole search model, but anyway >>>>history pruning is not the key to Fruit strength. >>>> >>>>To my mind, the key of Fruit strength is that the "Chess is the art of >>>>exchange". So, Fabien's idea about flexible game stages looks to be a beautiful >>>>way to improve positional play. Fruit can effectively consolidate the position. >>>>It simply knows when to excange to improve position. I think that it's the main >>>>key (cumulative with very good tuning of evaluation function). I think Fruit is >>>>very perspective. The main line of progress for this project, to my mind, is to >>>>add more complicated knowledge and intellectualize a search. >>>> >>>>2) Rybka >>>> >>>>Some time ago we discussed with Gian-Carlo Pascutto an idea of create special >>>>"SET-tables" with sets of piece-square values indexed by 1) material on the >>>>board; 2) king position; 3) pawn structure. Such tables can be calculated by >>>>analyzing a lot of games. That time I delayed my work in this area because I >>>>found other perspective things. >>>>You can see that Rybka executable contains a lot of precalculated tables. And >>>>also we all know that Rybka plays positional style. My version is that Rybka >>>>uses some variation of SET-approach. At all cases it uses some precalculated >>>>positional knowledge, but what sort of it? ;) >>> >>>My personal opinion: >>> >>>Fruit wins by 3 things: deep PV checking, mobility, and correctness. I talked >>>about this with Fabien at Reykjavik. When you have mobility, you are very >>>sensitive to being "driven back". And when you can check your mainline 18-20 >>>ply and not lose any mobility, its very probably you're playing a good move. >>> >>>Rybka: I'm starting to think that a lot of Rybka's strength is tactical. Try >>>that baby out on a few test positions some time. For example, the rapid TC CEGT >>>list has Rybka 55 rating points ahead of Fruit, while the slower BFF list has >>>Rybka only 15 rating points ahead of Fruit. >>> >>>anthony >> >>We need more data. I'll try to put it together when it's all ready. >> >>One thing people tell me is that Rybka tends to stick with her moves from lower >>depths more than other engines. This would also suggest better blitz play. >> >>Vas > >In past programs sticking to the same move and showing same mainline was very >common. We called it back then preprocessors. > >Vincent This is interesting. So if I toss the preprocessor, put in the same evaluation in the endpoint evaluation instead, my initial move in each iteration will more frequently change. That is interesting. I hope I did not misunderstand that.
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