Author: Vincent Diepeveen
Date: 17:02:37 09/02/02
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On September 02, 2002 at 19:29:17, Robert Hyatt wrote: >On September 02, 2002 at 17:15:54, Dave Gomboc wrote: > >>On September 01, 2002 at 13:26:44, Robert Hyatt wrote: >> >>>On September 01, 2002 at 09:40:34, Vincent Diepeveen wrote: >>> >>>>pawn=32 in fritz seemingly. that's all you need to know to consider >>>>it works for it. >>> >>>What does that do? I have seen large positional scores out of fritz, >>>which suggests (to me) that mtd(f) could cause some problems... >> >>It means there's a lower granularity of values, so less (re-)searches are >>required to arrive at the score. I have believed for some time that this is a >>correct decision, because I don't have confidence in the precision of even >>centipawn evaluations (much less the millipawn evaluations that Diep years ago >>when Vincent based mtd techniques heavily). I didn't know that Fritz actually >>had done it, though. >> >>The range of positional scores is relevant for lazy evaluation schemes, but I >>think that issue is pretty well handled by Don Dailey's recommendation. >> >>Dave > > >I understand that. But that wasn't the issue I was addressing. It was "fritz >uses a paw value of 32 or whatever..." And I don't see how that influences >mtd(f) as much as an evaluation that produces positional scores that vary from >+3.00 to -3.00, no matter what 1.00 means. If an evaluation can produce wild >positional scores, then mtd(f) causes problems... It makes it hard to hone in >on the right final score, particularly with lazy eval.. Fritz doesn't flip mainlines just like other programs do. In fact i'm still trying to conclude whether it forward prunes last so many plies or whether it is a result of very bad accuracy in evaluation (pawn=32 i suspect) or whether it is a result of using some kind of extra value sometimes to get a different move get the new PV (searching with A+something if the current mainline is having a bound at A). Many scenario's still opened here. But in a program X when using pawn=32 versus pawn=1000, that's a major difference. Fritz gets like 12 ply instantly and after that doesn't flip that quickly. World champs versions alway seem in my eyes to search less deeply than commercial versions are, though it is possible he just had a faster fritz version there and that i'm more patient at home than the 2 minutes a move you have there... Basically i advice you to get windows at one of your machine, and then you can see all these commercial programs yourself too and perhaps you can get more insight into the matters.
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