Author: Vasik Rajlich
Date: 12:35:55 12/16/05
Go up one level in this thread
On December 16, 2005 at 13:34:43, Uri Blass 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 > >I think that it may suggest simply that rybka is better because it needs less >time to find the correct moves unlike other engines that need big depth to find >the correct moves. > >I think that the only correct test is test with time handicap. >I think that it may be interesting to see how much time programs need to get 50% >against Rybka at 1 minute per game and the same for longer time control. > >I think that there is diminishing returns so if a program score better at blitz >but wins at all time controls then it is not fair to claim that it is better >blitz player. > >If you can prove that Rybka score 50% with time handicap of 3:1 at blitz against >engine X(ponder off) and score less than 50% with the same time handicap at >longer time control then you have a point. > >Uri Another topic we need some data about. Was it ever proven that engine differences are magnified at shorter time controls? It's not obvious to me. Vas
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