White's Win Against Black Ka3 and Pawns b5,d6

by Kenneth W. Regan

Diagram 1, White to move. To play Qf7 or not?

1. Qf7 Qe4+

Other checks lead to a quick win: 1...Qg5+ 2. Ke8 Qb5+ 3. Kf8 Qb8+ 4. Qe8+/-; 1...Qh4+ 2. Kd7! Qg4+ 3. Kc7+/- or 2...Qh3+ 3. Kd8 Qh4+ 4. Kc7+/-)

2. Qe6 Qb7+

3. Kf6 Qf3+

4. Qf5

Now 76...Qc3+ 77. Kg6 Qc4 (77...Qg3+ 78. Kf7 Qb3+ 79. Kf8+/-) 78. Qf3+! Kb2 79. Qf7 is the basic Qf7 win. Is this all Black has? No!

4. ... Qa8!

Diagram 2, White to move. This is a "little study": can you solve it?

5. Qg4! Qd8+

6. Kf7! Qc7+

7. Kg6 Qc2+

Instead, 7...Qd8/b8 8. Qe6 is +/-.

8. Kg5! ...

Now 8...Qc5+ 9. Kh4 is instant +/-, and 8...Qd2/c1+ 9. Kh4 Qh6+ 10. Kg3 is the same. And the desperate 8...Qh7 is met by 9. Qf3+ Kb2 10. Qf7+/-. However, an equally desperate-looking move poses White another challenge:

8. ... Qb3!

Diagram 3, White to move. This is also a "little study".

9. Qf5! and now:

  1. (i) 9...Qg8 10. Qa5+ Kb3 11. Kf6! (already MacChess 5.0.1 reports "+643") Qc4 12. Qh5! Ka3 (Queen checks lead to a deadly interposition) 13. Qf3+ Qc3+ 14. Qxb3 bxc3 15. g8=Q EGTB+/- #19.
  2. (ii) 9...Qg3+ 10. Kf6 b3 11. Qa5+ Kb2 12. Qd5! is a win that was known during the actual game: 12...Qf3/f4+ 13. Ke7 Qe3+ 14. Kf8 Qf4+ 15. Qf7 Qh6 16. Qf5 Ka1/a2 17. Kf7 b2 18. g8=Q b1=Q 19. Qa8+ and soon mates.
  3. (iii) 9...Qg3+ 10. Kf6 Qc3+ 11. Kg6! Qc4 12. Qf3+! Kb2 13. Qf7! is the basic Qf7 win.
  4. (iv) 9...Qe3+ 10. Kg6! Qe8+ 11. Kh7 Qe7 12. Qf4! +/-.
  5. (v) 9...Qc4 10. Qf3+ Kb2 11. Kf6 Qd4+ 12. Kg6 Qc4 13. Qf7 is the same as (iii).
  6. (vi) 9...Kb2/a2 10. Kg6! and either 70. Qf7 or 70. Kh7+/- next.
  7. (vii) 9...Ka4 (now 10. Qd7+ Ka3 11. Qa7+ Kb2 12. Kf6 wins, but snappier is) 10. Qe4! Qg3+ (...Qg8 70. Kf6 +/-) 11. Kf6 Qf2+ (11...Qc3+ 12. Kf7 Qc7+ 13. Kf8+/-) 12. Ke7 Qa7+ 13. Kf8 Qf2+ 14. Ke8 Qg3 (...d5 15. Qe6+/-) 15. Qa8+ and 16. Qd5+ +/-.

This looks over, but Black has a way to be annoying that MacChess 5.0.1 found:

(h) 9. ... Qg3+

10. Kf6 d5!

10...b3 11. Qa5+ Kb2 12. Qd5!

11. Qe5!

Now 11...Qf3+ 12. Ke7 Qg4/g2 13. Qa1+ Kb3 14. Qf6 K-moves 15. Qf7 Qe4/g5/h4+ 16. Kd7 Qg4+ 17. Kc7 Qc4+ 18. Kb6! Qd5+ 19. Kb7+/- is fairly straightforward, but the other check is better.

11. ... Qf2+

12. Kg6 Qg2+

12...Qb6+ 13. Qf6 transposes.

13. Kf7 Qf2+

13...Qf1/f3+ 14. Qf6+/-.

14. Qf6 Qa7+

Now 15. Qe7 Qf2+ 16. Ke8 Qg1! may be inconclusive---note that 17. Qf7 is not a win with Black's King at a3, and Black has denied White a check on a7. And, 17...Qe3+ 18. Kd8 Qb6+ 19. Qc7 Qg6 or 19. Kc8 Qa6/c6+ 20. Kb8 Qb6+ 21. Qb7 Qg6! 22. Qa7+ Kb3! or 22. Qa8+ Kb2! is inconclusive. So White goes the other way.

15. Kg6 Qb8

15...Qg1+ 16. Qg5 Qb6+ 17. Kh5+/-, or 16...Qb1+ 17. Kf7 Qf1+ 18. Qf6+/-.

Diagram 4. Take advantage of the swap of Black Qa8,Pd6 for Qb8,Pd5.

16. Qf3+! Kb2

17. Qf7!

Black avoided 16...Ka4 because 17. Qxd5! is EGTB+/- #22, with the finish being 17...Qg3+ 18. Kf7'' Qc7+ 19. Kf8!'' Qf4+ 20. Ke8'' Qe3+ 21. Kd8' Qb6+ 22. Kc8'' Qa6+ 23. Kc7'' Qa5+ 24. Kc6!'+/- (EGTB annotation key). But now 17. Qf7 is the basic Qf7 win with a Black pawn on d5.

White has an alternate win at Move 16 that may technically be quicker:

16. Kf5!? Qg3

16...Qc8+ 17. Kg5! Qc1+ 18. Qf4 Qg1+ 19. Qg4 Qc1/e3+ 20. Kh4 and soon +/-.

17. Qa1+ Kb3

18. Qd1+ Kb2

18...Ka2 loses the b-pawn with check, and 18...Ka3/c3 loses quickly to a 3rd-rank interposition following 19. Qg4.

19. Qg4! Qd3/f2+

20. Kg5 ...

Diagram 5. Point is that Black's d-pawn prevents ...Qd5+.

Now if 20...Qd2+ 21. Kg6 Qd3+ (21...Qc2+ 22. Qf5 Qg2+ 23. Kf7+/- or  22...Qc6+ 23. Qf6+ +/-) 22. Kf7 Qf1+ 23. Ke7 Qe1+ 24. Kd7+/- finally evades Black. The alternative shows how the "Cannon" theme works in classic fashion:

20. ... Qe3+

21. Kh4 Qh6+

22. Kg3 Qe3+

23. Kg2 Qd2+

24. Kf1! Qc1+

25. Kf2 Qc5+

26. Kg2 Qc2+

27. Kh1! Qh7+

28. Kg1 Qb1+

29. Kf2+/-.