Author: Peter Fendrich
Date: 14:18:24 03/02/04
Go up one level in this thread
On March 02, 2004 at 09:51:33, Uri Blass wrote: >On March 02, 2004 at 09:04:13, Peter Fendrich wrote: > >>On March 02, 2004 at 08:07:57, Sergei S. Markoff wrote: >> >>>Hello all! >>> >>>I post an answer to Cristophe's posting, but it was too close to message list's >>>end. >>> >>>>An idea I have played with, and which worked somehow in the 16 bits version of >>>>Chess Tiger is to: >>> >>>I'm using in SmarThink a scheme like you described but with some differences. >>>I'm searching some first moves, captures and extended moves to full depth. Other >>>moves I'm searching with reduced depth (the reducing amount depends of several >>>factors, for example if the opponent king safety is worse and it's a move that >>>going piece closer to opponent's king then reducing amount will be less e.t.c., >>>I'm using here a lot of knowledge including trajectories analysis e.t.c.). If >>>the reduced search returns value > alpha, I'm researching this move to full >>>depth. There are a lot of possibilities to include a lot of knowledge here to >>>build really knowledge-guided tree. >> >>Hi Sergei, >> >>I've tried similar things in Terra with no success at all and the key here is, >>as you point out, knowledge. My program is currently not structured for carrying >>a lot of knowledge in the interior nodes and that's of course why these things >>didn't work so well. I have only kept a few features. For instance reducing the >>depth for moves down in the move list that never (seldom) caused Fail High. >>(Kind of "reversed" History killer table). It seems to improve the program a >>tiny bit but not much... >> >>/Peter > >This is the only similiar pruning that I have in movei for more than a year(even >0.0799 is using that pruning). > >I believe that this is the pruning that sergei talked about in the past when he >talked about history based pruning(I implemented it independetly in movei before >he talked about it and was disappointed when he talked about it because I >understood that it means losing one relative advantage that movei has relative >to most programs and as an inferior programmer without some relative advantages >thanks to ideas I have no chance to compete). > >I believe that the main problem is to write the relevant functions to calculate >the relevant knowledge. > >My experience with history based pruning was that it clearly helped in test >suites(I was less sure about games but I decided to keep it and later made some >exceptions when not to use history based pruning). > >Uri I've lots of ideas around these concepts but it doesn't suit the basic structure of Terra very well. That's one of the reasons why I'm sketching on a completely new engine. One other reason is that I'm kind of bored of the pure bitboard technique these days... A combination of bitboards and a 0x88 version is the optimal IMHO. /Peter
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