Test position

[Terry McCracken]

what is the punch line after Nxd5 Nxd5???

It looks like 18...Nxd5 is good for a draw only, and probably a silent move like Bb7 may be better. But it is somewhat tricky, because after 18... Nxd5 19.Nxd5 Qxg5 20.Nxc7 f4, and again after 21.g4 Qh4, White does not have time to capture one of the rooks because of mate. But if he plays 22.Nb3 which defends against Bg7-d4, I think Black's best choice is to go for the perpetual with Qg3+ etc. Although I am not 100% sure if deeper analysis couldn't find an improvement for Black.

[Event "?""]
[Site "?"]
[Date "2007.07.17"]
[Round "?"]
[White "?"]
[Black "?"]
[Result "*"]
[SetUp "1"]
[FEN "r1b1r1k1/2p1q1bp/1p1ppnp1/p1nP1pB1/2P1P3/2N2PPP/PPQNB1K1/3R1R2 b - - 0 18"]
[PlyCount "14"]

18... Nxd5 19. Nxd5 Qxg5 20. Nxc7 f4 21. g4 (21. Nxa8 Qxg3+ 22. Kh1 Bd4 {
(no defense against Qxh3#)}) (21. Nxe8 Qxg3+ 22. Kh1 Qxh3+ {is a long mate.})
21... Qh4 22. Nb3 (22. Rh1 Qg3+ 23. Kf1 Bd4 {followed by Qf2#}) (22. Nxa8 Qg3+
23. Kh1 Bd4 {(again no defense against Qxh3#)}) (22. Nxe8 Qg3+ 23. Kh1 Bd4 24.
Nf6+ Kh8 {(same)}) 22... Qg3+ 23. Kh1 Qxh3+ 24. Kg1 Qg3+ 25. Kh1 *

Mike's analysis looks flawless. I missed the white knight fork at c7; I was too enamoured of the black threat of simultaneously forking king, queen, and 2 rooks. I really should run these positions overnight before posting! The position is busted!

But it's quite possible that Nxd5 is the best move...

Ron

I thought the point was to find the Best Move? 18..Nxd5! is the best move, and 19. Nxd5 is best for White, leaving Black a bit better.

Terry

[George Tsavdaris]

Just taking Spike's preferred move after a few seconds leads to this:

[d]4r1k1/6b1/1pbpp1p1/p1q5/2P1Pp2/5Pp1/PPQR2K1/3B1R2 w - - 0 17

Black has two pawns and the two bishops for the exchange, and Spike is quite happy. There are many variations possible, and this is unlikely to be best play. Even so, I'm not sure there's any real advantage here.

There is a better move in your line:

7.Bd3 which after:

7...Nxd3 8.Qxd3 white can draw almost easily, for example:

8...d5 9.Nxe8 Qxh3+ 10.Kg1 Qg3+ 11.Kh1 Rxe8 12.cxd5 exd5 13.Qb5 Qh3+ 14.Kg1 Re7 15.Rd2! =

[Dirt]

There is a better move in your line:

7.Bd3 which after:

7...Nxd3 8.Qxd3 white can draw almost easily, for example:

8...d5 9.Nxe8 Qxh3+ 10.Kg1 Qg3+ 11.Kh1 Rxe8 12.cxd5 exd5 13.Qb5 Qh3+ 14.Kg1 Re7 15.Rd2! =

Just to make sure I don't slander Spike, that particular move was from Bob's recommendation, and not Spike's analysis.

[Dirt]

There is a better move in your line:

7.Bd3 which after:

7...Nxd3 8.Qxd3 white can draw almost easily, for example:

8...d5 9.Nxe8 Qxh3+ 10.Kg1 Qg3+ 11.Kh1 Rxe8 12.cxd5 exd5 13.Qb5 Qh3+ 14.Kg1 Re7 15.Rd2! =

Spike still thinks this favors black. I followed several variations and got some black wins and some draws. Here is an example:

[Event "Edited game"]
[Site "GREGSIMP"]
[Date "2007.07.17"]
[Round "-"]
[White "-"]
[Black "-"]
[Result "*"]
[FEN "r1b1r1k1/2p1q1bp/1p1ppnp1/p1nP1pB1/2P1P3/2N2PPP/PPQNB1K1/3R1R2 b - - 0 1"]
1... Nxd5 2. Nxd5 Qxg5 3. Nxc7 f4 4. g4 Qh4 5. Nb3 Qg3+ 6. Kh1 Bb7 7. Bd3
Nxd3 8. Qxd3 Qxh3+ 9. Kg1 Qg3+ 10. Kh1 a4 11. Nxa8 d5 12. Nxb6 dxe4 13. Qd7
Qh4+ 14. Kg1 Re7 15. Qd8+ Kf7 16. Qd2 Qg3+ 17. Qg2 Qxg2+ 18. Kxg2 exf3+ 19.
Kh2 axb3 20. axb3 e5 21. Nd5 Bxd5 22. cxd5 g5 23. Rxf3 e4 24. Rh3 h6 25.
Kh1 Rb7 26. Rh2 e3 27. Rd3 Rc7 28. Rd1 Bf8 29. Re2 Kf6 30. Kg2 h5 31. Kf3
hxg4+ 32. Kxg4 Rh7 33. d6 Rh4+ 34. Kf3 Bxd6 35. Rxd6+ Ke5 36. Rdd2 g4+ 37.
Kg2 Kf5 38. Rxe3 fxe3 39. Rd8 Rh6 40. b4 Re6 41. Kf1 g3 42. Rg8 Kf4 43. b5
Rd6 44. Rf8+ Ke4 45. Re8+ Kd4 46. Ke2 Rg6 47. Kf1 Kd3 48. Rd8+ Kc4 49. Re8
g2+ 50. Kg1 Kd3 51. Rd8+ Ke4 52. Re8+ Kf3 53. Rf8+ Ke2 54. Re8 Rb6 55. Re5
Rd6 56. Kxg2 Rg6+ 57. Kh3 Kf2 58. Rf5+ Ke1 59. Rc5 e2 60. Rc6 Rg1 61. b6
Kd2 62. Rd6+ Kc2 63. Rc6+ Kb1 64. Re6 e1=Q 65. Rxe1+ Rxe1 66. b7 Re8 67. b4
Kb2 68. Kg4 Kc3 69. b5 Kc4 70. b6 Kc5 71. Kf5 Kxb6 72. b8=Q+ Rxb8
[Black will win]

There may have been an clear draw in there somewhere near the beginning, but Spike on my slow computer isn't able to find it easily.