Black to move and checkmate in 11. Can you find it without computer assistance?
3bk2r/1N1n1pp1/2Q1pn2/1P5p/P2P4/1B1qP2P/4rPP1/R2N2KR b k – 0 1
Daily Chess Improvement: Calculation required
About Author
Let’s see where this goes.
1… Re1+ 2. Kh2 Ng4+ seems like the obvious start. White has two choices here – Kg3 and hg. But 3. Kg3 gets mated by h4+ and Qf5#.
3. hg and black has to make a decision, 3… hg+ or 3… R:h1+. 3… R:h1+ seems better for two reasons – one, it removes the Rh1, which otherwise prevents …Bh4+, and two, it allows the Q into the attack at f1.
Let’s try 3… R:h1+. 4. Kh3 Bh4+ 5. Kf4 g5+ eventually gets mated by Qf5 as above, so the most stubborn defense seems to be 4. K:h1 Qf1+ 5. Kh2. The way seems clear from here.
5… hg+ 6. Kg3 Bh4+ (finally!) 7. Kf4 g5+ 8. K:g4 Qe2+ forces white to unpin the Nd2 by Qf3, since otherwise 9. f3 Q:g2 is mate and 9. Kh3 B:f2 is mate).
After 9. Qf3 Nf6+ 10. Kh3 B:f2+ 11. Qh5 allows black the choice of two mates.
… Re1
Kh2 Rh1
Kh1 Qf1
Kh2 Ng4
hg hg
Kg3 Rh3
gh3 Qh3
Kf4 g5
Kg5 Qh5
Kf4 Qg4
That’s only 10 – maybe White can extend it another move somehow by doing something like meeting Ng4 with Kg3?
Main Line that is longest with mate in 11 black moves:-
1. … Re1+
2. Kh2 Ng4+!
3. hxg4 Rxh8+
4. Kxh1 Qf8+
5. Kh2 hxg4+
6. Kg3 Bh4+
7. Kf4 g5+
8. Kxg4 Qe2+
9. Qf3 f5+
10. Kh3 Bf2+
11. Qh5 Rxh5#
Alternative Lines (to above main line) that are shorter with mates in 4 to 9 moves:-
If 3. Kg3…h4+ 4. Kxg4…Qf5#
If 3. Kg3…h4+ 4. Kf3…Qf5#
If 3. Kg3…h4+ 4. Kf4…Qf5#
If 4. Kg3…Bh4+ 5. Kf3…hxg4+ 6. Kf4…g5+ 7. Kxg4…Qf5#
If 4. Kg3…Bh4+ 5. Kf3…hxg4+ 6. Kxg4…Qf5#
If 4. Kg3…Bh4+ 5. Kf4…g5+ 6. Kf3…hxg4+ 7. Kxg4…Qf5#
If 7. Kh2…Bxf2#
If 7. Kxg4…Qe2+ 8. Kh3 ..Bxf2#
If 7. Kxg4…Qe2+ 8. Kf4 ..g5+ 9. Ke4..h5#
If 7. Kxg4…Qe2+ 8. Qf3 ..h5+ 9. Kf4 g5#
If 7. Kxg4…Qe2+ 8. F3 ..Qxg2+ 9. Kf4 g5#
If 8. Ke4…f4#
If 9. f3…Qxg2#
If 9. Kh3…Bxg7#
Harry
Main Line that is longest with mate in 11 black moves:-
1. … Re1+
2. Kh2 Ng4+!
3. hxg4 Rxh8+
4. Kxh1 Qf8+
5. Kh2 hxg4+
6. Kg3 Bh4+
7. Kf4 g5+
8. Kxg4 Qe2+
9. Qf3 f5+
10. Kh3 Bf2+
11. Qh5 Rxh5#
Alternative Lines (to above main line) that are shorter with mates in 4 to 9 moves:-
If 3. Kg3…h4+ 4. Kxg4…Qf5#
If 3. Kg3…h4+ 4. Kf3…Qf5#
If 3. Kg3…h4+ 4. Kf4…Qf5#
If 4. Kg3…Bh4+ 5. Kf3…hxg4+ 6. Kf4…g5+ 7. Kxg4…Qf5#
If 4. Kg3…Bh4+ 5. Kf3…hxg4+ 6. Kxg4…Qf5#
If 4. Kg3…Bh4+ 5. Kf4…g5+ 6. Kf3…hxg4+ 7. Kxg4…Qf5#
If 7. Kh2…Bxf2#
If 7. Kxg4…Qe2+ 8. Kh3 ..Bxf2#
If 7. Kxg4…Qe2+ 8. Kf4 ..g5+ 9. Ke4..h5#
If 7. Kxg4…Qe2+ 8. Qf3 ..h5+ 9. Kf4 g5#
If 7. Kxg4…Qe2+ 8. F3 ..Qxg2+ 9. Kf4 g5#
If 8. Ke4…f4#
If 9. f3…Qxg2#
If 9. Kh3…Bxg7#
Harry
I don’t see how it could start any other way than Re1, and I am pretty sure Ng4 has to be the second move, but mate in a 11 is a little beyond me at the moment unless I am willing to spend the next 2 hours on this.
1… Re1 + 2. Kh2 Ng4+ 3. hxg4
( 3.Kg3 h4+ 4.Kxg4 Qf5#)
Rxh1+ 4.Kxh1
(4.Kg3 Bh4+ 5.Kf4 g5 + 6.Kf3 hxg4 7. Kxg4 Qf5# )
Qf1 + 5.Kh2 hxg4 + 6.Kg3 Bh4+ 7.Kf4 g5+ 8. Kxg4 ( 8. Ke4 f5#) Qe2+ 9. Qf3+ ( 9.Kh3 Bxh2# ) f5+ 10. Kh3 Bxf2+ 11. Qh5 Rxh5#