Author: Uri Blass
Date: 09:29:32 03/08/02
Go up one level in this thread
On March 08, 2002 at 12:01:47, Robert Hyatt wrote: >On March 08, 2002 at 00:40:01, Dieter Buerssner wrote: > >>On March 07, 2002 at 22:50:05, Robert Hyatt wrote: >> >>>On March 07, 2002 at 22:45:55, Dieter Buerssner wrote: >>> >>>> 5b1k/3R4/5P2/p1rB4/8/8/6K1/8 b - - >>>> >> >>>>Perhaps I am too naive, but when I watched this game, I first was confident, >>>>that it should be a very easy draw. My (stupid?) reasoning was: A computer will >>>>not lose KRBKR (when he does not see the exceptional win fast). The position >>>>here is KRBPKRBP. The Bs are of opposite color. So, I thought, it should allways >>>>be possible, to sac one B for a P, and have an easy draw. Well, I was totally >>>>wrong, and so was the knowledge I coded into my engine. >>>> >>>>How long does your engine need, to avoid a4? How long does it need, to see a >>>>convincing winning score after a4? (Kg3 is a forced win, other moves perhaps, >>>>too). >> >>>Crafty decides a4 is not so good pretty quickly (on my laptop here)... >> >>Yes. >> >>> 12-> 58.63 1.45 1. ... Rb5 2. Rd8 Kh7 3. Be4+ Kg8 4. >>> Rd7 Rb2+ 5. Kg3 Rb6 6. Bd5+ Kh8 7. >>> Rf7 Bc5 8. Kf4 a4 >> >>This will draw. >> >>>If you force a4 and let it search for white: >>> >>> 11-> 19.99 2.18 2. Kf3 Rc1 3. Kf4 Rf1+ 4. Kg5 Re1 5. >>> Kg6 Rg1+ 6. Kf7 Bc5 7. Rd8+ Kh7 8. >>> Be4+ Kh6 9. Ke6 >> >>While the score does not look too convincing yet, Kf3 will win. >> >>Thanks for all the answers. However, I'd also be interested in comments about >>the "knowledge" above. Was this just bad luck? Or is it just stupid to assume, >>that KRBPKRBP with Bs of opposite color should be draw? >> >>Regards, >>Dieter > >I don't assume draw if both sides have pawns. It is too easy to get a B >pinned and let the pawn slip by If one side has a KRB and the other has >a KRBP then opposite B's should guarantee that the P can't win. I don't >try to get to fancy here because there are too many exceptions when both >sides have pawns... I do not think that 0.00 is a good idea because it means that the program does not care about the question if the king is in a bad square but I still believe that most KRBP vs KRBP with opposite color bishops are drawn so dividing the regular evaluation by 4 in this case to be closer to a draw does not seem to be too dangerous. Uri
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