1. Bc4!
1. b4+? Kb5! 2. Bc4+ Ka4 = zz with White to move
1... Ka4
1... Kb6 eg 2. b4+-
2. b4 zz with Black to move
2. Kc2? Kb4=
2...Ka3 3. b5 Nb3! 4. b6
4. Bxb3? Stalemate
4... Nc5 5. Bb3!
White too sacrifices on b3, showing the Umnov theme.
Logical try:
5. Bb5? Ne4+ 6. Kd4 Nd6 7. Kd5 Nb7 8. Kc6 Na5+ = White cannot use the b5 square for his king to push away the knight from a5.
5... Ne4+
White now wins with the plan outllined below. The key position after Black's 17th move
can be reached in a number of ways.
6. Kc4 Nd6+ 7. Kc5 Nb7+ 8. Kc6 Na5+ 9. Kb5
The king has access to this square thanks to White's 5th move.
9... Nb7
Now White must cover both e6 and b7 with the bishop from c8.
10. Be6 Nd8 11. Bc8 Kb3
White's king can approach.
12. Kc5 Ka4 13. Kd6 Ka5 14. Kc7 Kb5 15. Bg4 Ka5
15...Kc5 16. Bd7!
16. Bh3 Kb5 17. Bf1+ Kc5
Finally Black must be put in zugzwang.The winning plan up to now and the following trick is known from Vandecasteele 2012, Schaakstudiespinsels-2#061,
HHDBVI #8515. And even from the game Reshevsky - Ivkov, Palma de Mallorca 1970.
www.chessgames.com/perl/chessgame?gid=1063192
18. Bc4!
White begins and ends the study with this move trappping knights on c1 and d8.
18... Nc6 19. b7 +- 1-0
Vegetarian malyutka with Black and White sacrifices on the same square.
