Author: Zappa
Date: 16:53:44 12/20/05
Go up one level in this thread
On December 20, 2005 at 17:08:05, Stuart Cracraft wrote: >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. Small problem, Stuart: its not a preprocessor then :) anthony
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