Author: Robert Hyatt
Date: 15:20:33 08/13/00
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On August 13, 2000 at 16:21:34, Uri Blass wrote: >On August 13, 2000 at 15:12:25, Christophe Theron wrote: > >>On August 13, 2000 at 11:42:57, Mike S. wrote: >> >>>On August 13, 2000 at 10:59:22, pete wrote: >>> >>>>(...) >>>>[D]3r1rk1/2p1Rppp/p4n2/1p1b4/3P4/3B3P/PPPN2P1/4R1K1 b - - 0 1 >>> >>>It seems to me that Tiger, when playing 21...Bxa2?, cannot have expected 22.b3. >>>Maybe he expected something like 22.Rxc7 Rxd4 23.Ra1 Bd5 24.Rxa6 or similar. I >>>would be interested if Tiger "knows" this standard motif of locking up a bishop >>>after it captured a border pawn on the 2nd (7th) row. I think, in such cases the >>>lines beginnig with b3 etc. should be examined more closely than usual (?). >>> >>>Regards, >>>M.Scheidl >> >> >> >>Chess Tiger 12.0e has a partial knowledge of this "standard motif". It knows >>that the bishop is in trouble if it cannot leave a2, but the evaluation penalty >>I give in this case does not prevent it to take the pawn. >> >>That means that if another move could lead to a positional advantage, Tiger >>would play the other move. If there is no such move, Tiger will take the pawn >>with the bishop. >> >>I know it sounds a little bit strange, but I have been thinking about this >>problem for quite a while, and I have not found a good solution. For every >>example of a trapped bishop that gets lost I have seen the opposite example >>where the trapped bishop eventually escapes or completely shreds the side it has >>been trapped in, which leads to a big pawn majority and a winning endgame. > >The question is what happens in cases when you cannot find by a search of few >minutes that the bishop can escape and cannot find by a search of few minutes >that the bishop is trapped. > >I believe that in most of these cases moves like Bxa2 are wrong but I may be >wrong because I did not see a lot of examples when search cannot solve the >problem. > >Uri I prefer to be conservative here. Rather than trying (a) if the bishop isn't lost, then take the pawn, I prefer (b) if the bishop can't get off of a2 by the time the evaluation is called, then it is trapped. Works well for me, very inexpensive to test for.
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