V. Kalashnikov-S. Osintsev
Try I :
(1…Kb3? 2.Nd2+ Kc2 3.Nxf3 g1Q 4.Nxg1 Qxg1 5.Rxe8+-)
1…Kb2 2.Ba3+ Kc2 3.Bd3+!
a) 3.Ne3+? Kd2 4.Bb4+ Kc1 5.Ba3+ Kd2 6.Rd4+ Kxe3= positional draw.
b) 3.Bb3+? Kxb3 4.Rb4+ Kc2! 5.Rc4+ Kb1! 6.Nc3+ Kc2! 7.Nb5+ Kb1 8.Nd2+ Ka1! 9.Nb3+ Ka2 10.Nc1+ Ka1= positional draw.
3…Kxd3 4.Rd4+ Ke2
4…Kc2 5.Ne3+ Kb3 6.Rb4+ Ka2 7.Rb2+ Ka1 8.Nc2#
[5…Kxf1 6.Rd1+ Kf2 7.Bc5#]
6.Rd2+ Kg1! 7.Bc5+ f2
8.Rxf2 gxf1Q 9.Ra2+!
:a) 9.Rd2+? Qf2+ 10.Bxf2+ Kxh2 11.Bc5+ Qg2!=; Try IV : 9.Rc2+? Qf2+ 10.Bxf2+ Kxh2 11.Bg1+ Kxg1+ 12.Kg3 Qh6!=
b)9.Re2+? Qf2+ 10.Bxf2+ Kxh2 11.Bg1+
(11.Be3+ Qg2 12.Bf4+ Kg1=)
c) 9.Rb2+? Qf2+ 10.Bxf2+ Kxh2 11.Bg1+ Kxg1+ 12.Kg3 Qh7=
9…Qf2+ 10.Bxf2+ Kxh2 11.Bg1+! Kxg1+ 12.Kg3 Bb5! 13.Ra1+ Bf1 14.Ne2#
White starts the solution with successive checks with the aim of forcing Black into a self-obstruction. However, during this process he must avoid some tries with unique refutations. The four lines ending in checkmate, and especially the move 9.Ra2! are noteworthy. A nice study for solving.