Author: Serge Desmarais
Date: 19:21:08 09/10/98
Go up one level in this thread
On September 10, 1998 at 05:54:46, Moritz Berger wrote: >On September 09, 1998 at 20:15:12, Don Dailey wrote: > >>On September 09, 1998 at 11:34:10, Moritz Berger wrote: > >>>The Fritz PowerBook is compiled from a GM database with the only criterion for >>>including a game in the book being the playing strength of both players. >>> >>>The PowerBook doesn't contain *any* preferences to make Fritz prefer or avoid >>>any kind of opening lines, except of course the statistics from the human >>>database (win/loss/draw ratio and move frequency as well as ELO performance >>>which Fritz doesn't use AFAIK). It's basically just a good database, nothing >>>more and doesn't include any previous Fritz games. >>> >>>Moritz >> >>Moritz, >> >>I was under the impression that they used a learning process of some >>kind. I got this directly from Franz although he provided little >>detail. He was disapointed after getting a bad result at some >>tournament and thought perhaps the idea was no good. I also got >>the impression he was not directly involved in the programming of >>the book learning method but I don't know this for sure. > >Fritz does learning, of course. But the PowerBook doesn't have any pre-learned >parameters for the Fritz engine, it learns as the matches against other >opponents (no matter if human or silicon) go along. Implication: Fritz plays all >1.e4 1.d4 1.c4 1.Nf3, all popular responses to 1.e4 e.g. e5, c5 ,e6 you-name-it. >As long as a particular opening has enough followers among IM and GM players, >Fritz will play this, too. One weakness in Fritz' approach is that it even >follows games with only 1 occurence in the database up to the very last book >move, unlike Crafty where you can specify e.g move frequency >2 to blindly >follow a path. > >>But soon after Franz telling me about this I notice Fritz shoot >>to the top of the rating list. In my mind I suspected this was >>related to the book work I knew they had done but it was only a >>guess and I have no way to know. It could be a completely >>unrelated event for all I know. > >The book learning works quite well at the SSDF, but - unlike anybody else - >Fritz doesn't even have a start.PGN file like Crafty to influence the most basic >preferences, i.e. 1.d4 over c4 and so on. It gets into closed positions and >positions it doesn't understand too well (from a human point of view) quite >often, but at the SSDF it only plays other programs that face similar "computer" >problems with these positions so it doesn't get punished as much as it would >against humans. A good example is the fact that Fritz plays 1.c4 (and gets >punished against several opponents for doing so), but still scores the usual >~70% at the SSDF as far as I remember ... > >>So I am curious about where you got this information. Is this common >>knowledge, part of the chessbase documentation or did you learn >>this from some other source? > >Matthias Wüllenweber described somewhere in detail how he built the PowerBook >(he named the databases and ELO strength selection criteria he used). > >Fritz shows book weightings for all move in the "tree" view, they are all 0 by >default, the resulting move probabilities (which are also shown) correspond to >the underlying database results (that are also visible on the same line). > >But of course I don't trust ChessBase and have built many own books, ranging >from 400 MB to 2.7GB in size from various databases of different quality. >Results didn't differ much from the results with Fritz' PowerBook. Fritz even >got 50% in >30 tournament games with a book I built from 1000 Anand games >against another TOP 5 program... > >Conclusion: Fritz has demonstrated that opening books don't matter enough to >keep a program away from the #1 at the SSDF, although it might have scored even >better with a customized book. > >> I am pretty interested in knowing this >>myself and you seem to be in the know here. From what you are saying I >>am starting to believe they have a completely separate in-house book >>they use and Fritz got it's impressive results without any special >>book work or tuning of any kind. > >Chessbase did use a tournament book in the Frankfurt rapid chess event, but this >book is not available to the SSDF. Of course, using a custom tailored book is >even better than playing with a database dump ... > > >Moritz You surprise me, here, when you say that Fritz plays opening moves with ONE occurence! On my computer, all the moves that are unique get a 0% chance of being played. Of course, if all the moves in a given position were played less than 10 times, that is another story. Did you set your parameters for Fritz to play a greater diversity of moves than the default settings? Serge Desmarais
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