Author: John Merlino
Date: 11:32:09 12/13/02
Go up one level in this thread
On December 13, 2002 at 14:10:02, Omid David Tabibi wrote: >On December 13, 2002 at 12:25:55, John Merlino wrote: > >>On December 13, 2002 at 11:11:07, Omid David Tabibi wrote: >> >>>On December 13, 2002 at 10:44:47, Vincent Diepeveen wrote: >>> >>>>On December 12, 2002 at 15:56:43, Omid David Tabibi wrote: >>>> >>>>[snip] >>>>>Finding 13.Bb5 should be very easy for every computer. This opening was first >>>>>introduced in a match between national teams of USSR and Argentina. The >>>>>Argentinians played this opening on several boards (not expecting 13.Bb5), all >>>>>the Russian Grandmasters found 13.Bb5 and went on to crush black. >>>> >>>>where is the output of genesis? >>> >>>White(13): f1b5 >>>[book] >>> >>>;-) >>> >>>>Vincent >> >>This is the same with CM9000, and 13...Rh7 is also in the book (but no further >>moves). So, in a sense, the engine doesn't even NEED to find that move. I was >>using the analysis feature in my previous posts about this position, and this >>feature does not access the opening book. >> >>FYI, the CM8000 book plays 8...Qc7 in this line, and does not have any response >>to 8...h6. >> >>So maybe I DID make (or, rather, GENERATE) some improvements to the CM9000 book, >>eh? >> > >Now the CM's opening book consists of more data, but is this extra data useful >(if not dangerous)? It depends. Is CM aware of the drawish nature of the >Gothenburg variation? For example, if CM is playing for a win, will it "know" to >avoid the Gothenburg variation and instead head for the classical 8...Qc7 ? > >P.S. If black is playing for a win, he'd better avoid playing 7...Be7 in this >variation, and instead, play 7...Qb6 heading towards the poisoned pawn >variation. Here is what is in the CM9000 default opening book at the moves you have mentioned: After 7.f4 -- 7...Qb6, 1/4 probability -- 7...Be7, 1/4 -- 7...Nbd7, 1/6 -- 7...Qc7, 1/6 -- 7...b5, 1/6 Also, the moves 7...Bd7, 7...Nc6 and 7...h6 are in the book but have zero probability. After 8.Qf3 -- 8...Qc7, 3/4 probability -- 8...h6, 1/4 probability Also, the move 8...Nbd7 is in the book but has zero probability. The default CM book has always been designed to be eclectic, with the ability to play both popular lines as well as winning lines (which, in most cases, overlap, obviously). With CM9000, we used a completely new set of data to create the book, but we still focused on popularity as well as success to calculate the probabilities of the moves. No fine-tuning was done to this book after it was created, however.... The import PGN feature of the opening book editor in CM9000 has the ability to use different parameters to calculate the probablity that a move will be selected. I will take the liberty of creating a test book using the same data that was used to create the default book, except using winning percentage as the main parameter, rather than frequency. This will take several hours, after which I will report whether there is any significant difference in these two positions. <I guess I have a lot of time on my hands these days....> jm
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