User:Qwertyxp2000/Two bishops checkmate

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The two bishops checkmate in chess is the checkmate of a lone king by the opponent's two bishops and king.[a] The superior side is able to drive the lone king into a corner and force mate using the two bishops and king collaboratively. The only stipulation is that the two bishops must move on opposite-colored squares.[b][2] Accomplishing the mate requires a maximum of 18 moves.

Three basic checkmate positions are possible:[3]

abcdefgh
8
a8 black king
c7 white king
b6 white bishop
e4 white bishop
8
77
66
55
44
33
22
11
abcdefgh
Checkmate with two bishops and a king
abcdefgh
8
a7 black king
b7 white bishop
c7 white king
c5 white bishop
8
77
66
55
44
33
22
11
abcdefgh
An alternate mate
abcdefgh
8
a5 black king
b5 white bishop
c5 white king
d2 white bishop
8
77
66
55
44
33
22
11
abcdefgh
An alternate mate, but cannot be forced

Method[edit]

Fine, No. 3[3]
abcdefgh
8
f4 black king
g4 white bishop
h4 white bishop
a1 white king
8
77
66
55
44
33
22
11
abcdefgh
White to move mates in 18 with best play.

The king and bishops cooperate to drive the enemy king to an edge of the board, and then into a corner to deliver the mate.[1] "The process, though a bit lengthy, is fascinating because it gives us a glimpse of the power of the two bishops on the open board."[4]

 1. Bd1 Ke3 2. Kb2 Kd2 3. Bc2 Ke3 4. Kc3 Kf3
Or
  • 4...Ke7 5.Bg5 Kf3 6.Kd2 Kg4 7.Be3 Kf3 8.Bf5 Kg2 9.Ke2 Kg3 10.Bg5 Kg2 11.Bf4 Kg1 12.Kf3 Kf1 13.Bd2 Kg1 14.Kg3 Kf1 15.Bd3+ Kg1 16.Be3+ Kh1 17.Be4#.
  • 4...Kf4 5.Bd3 Kf3 6.Kd4 Kg4 7.Be1 Kf3 8.Bd2 as above.
 5. Kd4 Kg4 6. Be1 Kf3 7. Bd3 Kf4 8. Be4 Kg5 9. Ke5 Kg4 10. Bf2 Kg5
Or 10...Kh3 11.Kf4 Kh2 12.Kf3 Kh3 13.Bd3 Kh2 14.Bf1 Kh1 15.Be3 Kh2 16.Kf2 Kh1 17.Bg2+ Kh2 18.Bf4#.
 11. Bf5 Kh6 12. Kf6 Kh5 13. Be6 Kh6 14. Bg4 Kh7 15. Kf7 Kh6 16. Be3+ Kh7 17. Bf5+ Kh8 18. Bd4#

See also[edit]

Notes[edit]

  1. ^ "Against one knight or one bishop the defender cannot lose even if he wants to."[1]
  2. ^ Only an underpromotion can result in bishops on same-colored squares.

References[edit]

  1. ^ a b Fine 1979, p. 1.
  2. ^ Fine 1979, p. 4, "Two bishops of the same color cannot administer mate; a mating position is not even conceivable. The same holds true of nine (or more!) bishops all of one color."
  3. ^ a b Fine 1979, p. 3.
  4. ^ Reinfeld, Fred (1959). The Complete Chess Course. Doubleday & Company, Inc. p. 330. ISBN 0385004648.

Bibliography