%TITLE Longest mate in King and Bishop versus King and Bishop endgame: an endgame analysis by Joe Leslie-Hurd
%HEADING Longest mate in King and Bishop versus King and Bishop endgame
%SUBHEADING Mate in 1
%FOOTER An <a href="http://www.gilith/chess/endgames">endgame analysis</a> by <a href="http://www.gilith.com/">Joe Leslie-Hurd</a> on 16 February 2005.

[Event "Endgame analysis: longest mate in King and Queen versus King and Knight"]
[Site "Oxford ENG"]
[Date "2005.02.16"]
[Round "-"]
[White "Perfect"]
[Black "Perfect"]
[Result "1-0"]
[Time "05:52:17"]
[Annotator "Joe Leslie-Hurd"]
[WhiteType "program"]
[BlackType "program"]
[SetUp "1"]
[FEN "8/8/8/8/8/2k5/1n2Q3/3K4 w - - 0 1"]

{Mate in 21 with Kc1 and Ke1. Worse is Qxb2+ which throws away the win.}
1. Ke1 {White mates in 20 after Nd3+. Worse are Nc4 when White mates in 15, Na4 when White mates in 13, Kb3 when White mates in 11, Kb4 and Kd4 when White mates in 9, and Nd1 when White mates in 7.}
1... Nd3+ {Mate in 20 with Kf1. Worse are Kd1 with mate in 22, and Qxd3+ which throws away the win.}
2. Kf1 {White mates in 19 after Kd4. Worse are Nc5 when White mates in 15, Kc4 and Nb4 when White mates in 14, Nb2 and Nc1 when White mates in 13, Nf4 when White mates in 10, Kb3, Kb4, Ne1 and Nf2 when White mates in 8, and Ne5 when White mates in 7.}
2... Kd4 {Mate in 19 with Qd2, Qe6, Qe7 and Qe8. Worse are Qa2, Qc2, Qd1, Qf3, Qg2, Qg4+, Qh2 and Qh5 with mate in 20, Kg1 with mate in 21, and Kg2, Qb2+, Qe1, Qe3+, Qe4+, Qe5+, Qf2+ and Qxd3+ which throw away the win.}
3. Qe6 {White mates in 18 after Ne5 and Nf4. Worse are Nb4 when White mates in 16, Kc5 when White mates in 15, Kc3 and Nc5 when White mates in 14, Nc1 when White mates in 12, Nb2 when White mates in 11, and Ne1 and Nf2 when White mates in 7.}
3... Nf4 {Mate in 18 with Qd6+. Worse are Qc6, Qe7, Qe8 and Qg4 with mate in 19, Qa2, Qa6, Qb3, Qb6+, Qc8, Qd7+, Qe1, Qf5, Qf6+, Qf7, Qg8 and Qh6 with mate in 20, and Ke1, Kf2, Kg1, Qc4+, Qd5+, Qe2, Qe3+, Qe4+, Qe5+, Qg6 and Qh3 which throw away the win.}
4. Qd6+ {White mates in 17 after Ke4 and Nd5. Worse are Ke3 when White mates in 16, Kc4 when White mates in 9, and Kc3 when White mates in 7.}
4... Ke4 {Mate in 17 with Kf2. Worse are Ke1, Kg1, Qa3, Qa6, Qb4+, Qb6, Qb8, Qc5, Qc6+, Qc7, Qd2, Qd7, Qd8, Qe7+, Qf6, Qf8 and Qh6 with mate in 19, Qd1 with mate in 20, and Qd3+, Qd4+, Qd5+, Qe5+, Qe6+, Qg6+ and Qxf4+ which throw away the win.}
5. Kf2 {White mates in 16 after Nd3+ and Nd5. Worse are Kf5 when White mates in 14, Nh3+ when White mates in 11, Nh5 when White mates in 9, Ng6 when White mates in 8, Ne6 when White mates in 7, Ng2 when White mates in 6, and Ne2 when White mates in 5.}
5... Nd5 {Mate in 16 with Kg3 and Qc5. Worse are Qc6, Qd7, Qd8, Qe6+, Qf8, Qg3 and Qg6+ with mate in 17, Ke1, Ke2, Kf1, Kg1, Kg2, Qa3, Qa6, Qb8, Qh2 and Qh6 with mate in 18, and Qb4+, Qb6, Qc7, Qe5+, Qe7+, Qf4+, Qf6 and Qxd5+ which throw away the win.}
6. Qc5 {White mates in 15 after Nf4. Worse are Ke5 and Nf6 when White mates in 14, Nb4 and Ne3 when White mates in 9, Kf5, Nb6, Nc3, Nc7 and Ne7 when White mates in 8, Kd3 when White mates in 7, and Kf4 when White mates in 4.}
6... Nf4 {Mate in 15 with Qe3+. Worse are Qe7+ with mate in 16, Kg3, Qb4+, Qc2+, Qc3, Qc4+, Qc6+ and Qd6 with mate in 17, Kf1, Kg1, Qa3, Qa5, Qa7, Qb5, Qb6, Qc7, Qc8 and Qf8 with mate in 19, and Ke1, Qc1, Qd4+, Qd5+, Qe5+, Qf5+, Qg5 and Qh5 which throw away the win.}
7. Qe3+ {White mates in 14 after Kf5. Worse is Kd5 when White mates in 9.}
7... Kf5 {Mate in 14 with Kf3. Worse are Qd4 with mate in 15, Kg3, Qa3, Qb3, Qc3, Qc5+, Qd2, Qf3 and Qg3 with mate in 16, Qa7, Qb6, Qe7 and Qe8 with mate in 17, Kf1 with mate in 18, Kg1 with mate in 19, and Ke1, Qc1, Qd3+, Qe1, Qe2, Qe4+, Qe5+, Qe6+, Qh3+ and Qxf4+ which throw away the win.}
8. Kf3 {White mates in 13 after Ne6. Worse are Ng6 and Nh5 when White mates in 12, Nh3 when White mates in 10, Nd5 when White mates in 8, Nd3 and Ng2 when White mates in 7, Kg5 and Ne2 when White mates in 6, and Kf6 and Kg6 when White mates in 5.}
8... Ne6 {Mate in 13 with Kg3. Worse are Qe4+ with mate in 14, Ke2, Qc3 and Qd3+ with mate in 15, Kf2, Qd2, Qf2 and Qh6 with mate in 16, Kg2, Qa7, Qb6, Qc1, Qe1 and Qg1 with mate in 17, Qa3 with mate in 18, and Qb3, Qc5+, Qd4, Qe2, Qe5+, Qf4+, Qg5+ and Qxe6+ which throw away the win.}
9. Kg3 {White mates in 12 after Ng5. Worse are Kf6 and Ng7 when White mates in 11, Nc7 and Nf8 when White mates in 9, Nd8 and Nf4 when White mates in 8, Nc5 and Nd4 when White mates in 7, and Kg6 when White mates in 6.}
9... Ng5 {Mate in 12 with Qf4+. Worse are Qc5+, Qd3+ and Qf2+ with mate in 14, Kf2, Qd4 and Qg1 with mate in 16, Qa3, Qa7, Qb6, Qc1, Qe1, Qe2, Qe7 and Qe8 with mate in 17, Kg2 and Kh2 with mate in 18, Kh4 and Qb3 with mate in 19, and Qc3, Qd2, Qe4+, Qe5+, Qe6+, Qf3+ and Qxg5+ which throw away the win.}
10. Qf4+ {White mates in 11 after Kg6. Worse is Ke6 when White mates in 8.}
10... Kg6 {Mate in 11 with Kg4 and Qe5. Worse are Kh4 and Qf1 with mate in 12, Qb4, Qb8, Qc1, Qc4, Qd4, Qd6+, Qe3, Qf8, Qg4 and Qh4 with mate in 13, Kg2, Kh2, Qa4 and Qc7 with mate in 14, and Kf2, Qd2, Qe4+, Qf2, Qf3, Qf5+, Qf6+, Qf7+ and Qxg5+ which throw away the win.}
11. Qe5 {White mates in 10 after Nf7. Worse are Kf7 and Nh7 when White mates in 8, Kh5, Kh6, Ne4+, Ne6, Nf3 and Nh3 when White mates in 6, and Kh7 when White mates in 5.}
11... Nf7 {Mate in 10 with Qe6+. Worse are Qd5, Qe4+, Qe7, Qe8 and Qf4 with mate in 12, Qa5, Qb5, Qc5, Qc7 and Qd4 with mate in 13, Qb8, Qc3 and Qe2 with mate in 14, Qa1, Qb2, Qe1 and Qe3 with mate in 15, and Kf2, Kf3, Kf4, Kg2, Kg4, Kh2, Kh3, Kh4, Qd6+, Qf5+, Qf6+, Qg5+, Qg7+, Qh5+ and Qh8 which throw away the win.}
12. Qe6+ {White mates in 9 after Kg7. Worse are Kh7 when White mates in 6, and Kg5 and Kh5 when White mates in 5.}
12... Kg7 {Mate in 9 with Kg4. Worse are Kf4, Kh4, Qb6, Qe7 and Qf5 with mate in 10, Qa6 and Qe1 with mate in 11, Kf2, Kg2, Kh2, Qc6, Qd5, Qd7, Qe2, Qe3, Qe4 and Qe8 with mate in 12, Qa2, Qb3, Qc4, Qc8 and Qg4+ with mate in 13, Qh3 with mate in 14, and Kf3, Kh3, Qd6, Qe5+, Qf6+, Qg6+, Qh6+ and Qxf7+ which throw away the win.}
13. Kg4 {White mates in 8 after Nh6+. Worse are Nd8 when White mates in 6, Kf8, Kg8, Kh7, Kh8, Nd6, Ne5+ and Nh8 when White mates in 5, and Ng5 when White mates in 4.}
13... Nh6+ {Mate in 8 with Kh5. Worse are Kf3, Kf4, Kg3, Kg5, Kh3 and Kh4 with mate in 10, and Qxh6+ which throws away the win.}
14. Kh5 {White mates in 7 after Ng8. Worse are Kh7, Nf7 and Ng4 when White mates in 5, Kh8 when White mates in 4, Nf5 when White mates in 3, and Kf8 when White mates in 2.}
14... Ng8 {Mate in 7 with Kg5. Worse are Kg4, Kh4, Qc4, Qc6 and Qg6+ with mate in 9, Qa2, Qa6, Qb3, Qb6, Qc8, Qe5+, Qf5 and Qg4+ with mate in 10, Qd7+ and Qe3 with mate in 11, Qe1 and Qh3 with mate in 12, Qe2 with mate in 13, Qd6 with mate in 14, and Qd5, Qe4, Qe7+, Qe8, Qf6+, Qf7+, Qh6+ and Qxg8+ which throw away the win.}
15. Kg5 {White mates in 6 after Kf8. Worse are Nh6 when White mates in 5, Kh7 when White mates in 4, and Kh8, Ne7 and Nf6 when White mates in 3.}
15... Kf8 {Mate in 6 with Qd7. Worse are Kf5 with mate in 7, Kf4, Kg4, Kg6, Kh4, Kh5, Qa2, Qb3, Qc4, Qd5 and Qg6 with mate in 8, Qa6, Qb6, Qc6, Qc8+, Qd6+, Qe3, Qe4 and Qe5 with mate in 9, Qe1, Qe2, Qf5+ and Qh3 with mate in 10, Qg4 with mate in 11, and Qe7+, Qe8+, Qf6+, Qf7+, Qh6+ and Qxg8+ which throw away the win.}
16. Qd7 {White mates in 5 after Ne7. Worse are Nf6 and Nh6 when White mates in 2.}
16... Ne7 {Mate in 5 with Kf6. Worse are Kf4, Kg4, Kh4, Kh5, Kh6, Qa7, Qb7, Qd4, Qd6, Qd8+ and Qe6 with mate in 7, Qa4, Qb5, Qd1, Qd2 and Qd3 with mate in 8, Qc7, Qg4 and Qh3 with mate in 9, and Qc6, Qc8+, Qd5, Qe8+, Qf5+ and Qxe7+ which throw away the win.}
17. Kf6 {White mates in 4 after Ng8+. Worse are Nd5+ when White mates in 3, Kg8 when White mates in 2, and Nc6, Nc8, Nf5 and Ng6 when White mates in 1.}
17... Ng8+ {Mate in 4 with Ke6. Worse are Ke5, Kf5, Kg5 and Kg6 with mate in 6.}
18. Ke6 {White mates in 3 after Ne7. Worse are Nh6 when White mates in 2, and Nf6 when White mates in 1.}
18... Ne7 {Mate in 3 with Qxe7+. Worse are Qd4 with mate in 4, Kf6, Qd3 and Qd6 with mate in 5, Qa4, Qa7, Qb5, Qb7, Qc7, Qd1, Qd2 and Qd8+ with mate in 6, Ke5 with mate in 7, Kd6 with mate in 8, and Qc6, Qc8+, Qd5 and Qe8+ which throw away the win.}
19. Qxe7+ {White mates in 2 after Kg8.}
19... Kg8 {Mate in 2 with Kf6. Worse are Ke5, Kf5, Qa7, Qb7, Qc7, Qd7 and Qg5+ with mate in 3, Kd5, Kd6, Kd7, Qa3, Qb4, Qc5, Qd6, Qd8+, Qe8+, Qf6, Qf7+ and Qh4 with mate in 4, and Qf8+, Qg7+ and Qh7+ which throw away the win.}
20. Kf6 {White mates in 1 after Kh8.}
20... Kh8 {Mate in 1 with Qg7#. Worse are Kf7, Kg6, Qa7, Qb7, Qc7, Qd7 and Qf8+ with mate in 2, Ke5, Ke6, Kf5, Kg5, Qa3, Qb4, Qc5, Qd6, Qd8+, Qe1, Qe2, Qe3, Qe4, Qe5, Qe6 and Qe8+ with mate in 3, and Qf7 and Qh7+ which throw away the win.}
21. Qg7# {Checkmate.} 1-0
