Author: John Merlino
Date: 15:25:18 12/13/02
Go up one level in this thread
On December 13, 2002 at 14:57:12, Omid David Tabibi wrote: >On December 13, 2002 at 14:32:09, John Merlino wrote: > >>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. > >In addition to the probability, a gross evaluation is also essential for optimal >tournament play. For example, if it is playing for a win, it should eliminate >all drawish lines (i.e., set their probability to 0) from the list of choices. I don't know if this is such a good idea, and I think it can be rather dangerous. If the program is playing for a win, and there are no known "winning" moves (however that is defined), then the engine will have to decide what to play, rather than falling back on a "drawing" move and waiting to see what the opponent does. This idea is only as good as the engine's ability to play an opening, and, for most engines, this is the weakest part of their game. >BTW, under perfect play by both sides, 13.Bb5 leads into a draw, that is why >13.Bc4 has become more popular in the last years. But does 13.Bc4 win, or is it still unclear? There is nothing wrong with choosing a drawing move when you don't know of anything better. 13.Bc4 is not in the CM9000 opening book. Additionally, I discovered that if Black plays 13...Kg7, White will play the following line (assuming Black plays along): 14.0-0 Ne5 15.Bg3 Ng6 16.gxh6+ Rxh6 17.Rf7+ Kxf7 18.Qxh6 axb5 19.Rf1+ Ke8 20.Qxg6+ jm
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