Author: Jeremiah Penery
Date: 19:44:15 04/20/99
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On April 20, 1999 at 21:44:00, Dave Gomboc wrote: >Here's a "real position", that is, one that has actually been reached in games. >It is from the Marshall Gambit in the Ruy Lopez. > >1. e4 e5 2. Nf3 Nc6 3. Bb5 a6 4. Ba4 Nf6 5. O-O Be7 6. Re1 b5 7. Bb3 O-O 8. >c3 d5 9. exd5 Nxd5 10. Nxe5 Nxe5 11. Rxe5 c6 12. d4 Bd6 13. Re1 Qh4 14. g3 >Qh3 15. Be3 Bg4 16. Qd3 Rae8 17. Nd2 Re6 18. a4 f5 19. Qf1 Qh5 20. f4 bxa4 >21. Rxa4 Rb8 22. Bxd5 cxd5 23. Qg2 Qe8 24. Qxd5 Kh8 25. Kf2 g5 26. Rxa6 >Rxb2 27. Ra2 gxf4 28. gxf4 Rxa2 29. Qxa2 Bxf4 30. Nf1 Qe7 * > >Now, White can (and I think should) play 31. Qxe6 here. What is Black's best >response? Well, if 31...Qh4+ leads to perpetual, then it is best, otherwise >31...Qxe6 will probably have to do. > >Crafty 16.6 (dual PII-300) appears to think that the position is a draw: <snip> > 4-> 0.09 0.99 31. Qxe6 Qxe6 32. Bxf4 Qd5 <snip> > 13-> 5:48 0.00 31. ... Qh4+ 32. Kg2 Qh3+ 33. Kf2 Qh4+ > 14 7:51 -- 31. ... Qh4+ >White(31): quit >execution complete. >I am not very good with operating crafty from the command line: I could not tell >it to "go to infinite time control mode and think on a move". But it seems like >this ponder search should be sufficient. I think the ponder search is OK, but you need only type 'analyze' to enter the true 'infinite thinking' mode. :) >Anyway, once I get to the position after Qh4+, Crafty decides to play 32. Kg1 in >under 3 seconds, with a large score (> 3 pawns). So why was it taking so long >to see this in the ponder search? I am not sure if it is a symptom of a search >going haywire, or merely a run-of-the-mill bug. :/ It looks possibly like a null-move problem to me...Did you try this with any engines that use null-move and see what you get? >How do other programs handle this position? Oh, and could someone on the crafty >email list please post this there for Bob, since he doesn't seem to be around on >CCC anymore. I'll pass it along. >Dave
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