Author: Omid David Tabibi
Date: 15:35:39 12/13/02
Go up one level in this thread
On December 13, 2002 at 18:25:18, John Merlino wrote: >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? It is still unclear. But at least it doesn't lead into a forced draw... >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+ > Yes, I posted that variation yesterday. Here is the game I was referring to: Gligoric,Svetozar (2600) - Fischer,R (2785) [B98] FIDE (23) 1958-1960 Portoroz izt, 1958 1.e4 c5 2.Nf3 d6 3.d4 cxd4 4.Nxd4 Nf6 5.Nc3 a6 6.Bg5 e6 7.f4 Be7 8.Qf3 h6 9.Bh4 g5 10.fxg5 Nfd7 11.Nxe6 fxe6 12.Qh5+ Kf8 13.Bb5 Rh7 [13...Kg7 14.0-0 Ne5 15.Bg3 Ng6 16.gxh6+ Rxh6 17.Rf7+ Kxf7 18.Qxh6] 14.Qg6 Rf7 15.Qxh6+ Kg8 16.Qg6+ Rg7 17.Qxe6+ Kh8 18.Bxd7 Nxd7 19.0-0-0 Ne5 20.Qd5 Bg4 21.Rdf1 Bxg5+ 22.Bxg5 Qxg5+ 23.Kb1 Qe7 24.Qd2 Be6 25.g3 Rd8 26.Rf4 Qg5 27.Qf2 Kg8 28.Rd1 Rf7 29.b3 Qe7 30.Qd4 Ng6 31.Rxf7 Qxf7 32.Qe3 ½-½ >jm
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