[4] A method for checkmate applicable when the lone king is in the corner of the opposite color from the bishop (the "wrong" corner, where checkmate cannot be forced), was given by François-André Danican Philidor in the 1777 update[5] to his famous 1749 treatise, L'Analyse des Échecs.
Another method, known as "Delétang's Method" or "Delétang's Triangles",[7] applicable when the lone king is unable to reach the longest diagonal of the color opposite to that of the bishop, involves confining the lone king in a series of three increasingly smaller triangles, ultimately forcing it into a corner of the same color as the bishop (the "right" corner).
Some of the ideas of this method date back to 1780, but the complete system was first published in 1923 by Daniel Delétang.
[8] The method as propounded is not optimal, but it is relatively simple; so long as White has trapped the king behind the diagonal in a reasonable number of moves, it will lead to mate before the fifty-move rule takes effect.
[12] On the other hand, while Grandmaster Andy Soltis concedes that he has never played this endgame and most players will never have it in their career, he argues that learning the checkmate teaches techniques that can be applied elsewhere.
[14] Finally, the checkmate occurred in at least one very notable case: Tal Shaked's victory over Alexander Morozevich in the penultimate round of the 1997 World Junior Chess Championship.
[15] Shaked knew the correct mating pattern, and his victory catapulted him to becoming World Junior Champion, whereas a draw would have prevented him from winning the title.
Since White has a light-squared bishop, the knight must be used to control the dark squares on the 8th rank, forcing the black king to the h1-square.
The winning procedure consists of forcing the king to move towards the corner so that the bishop can reach the hypotenuse of the next smaller triangle.
A drawing trap was noted by the American master Frederick Rhine in 2000 and published in Larry Evans' "What's the Best Move?"
PGN text ➤ The ending of the game between Mika Karttunen and Vitezslav Rasik[26] at the 2003 European Chess Club Cup shows the knight's W manoeuvre.
PGN text ➤ Position V is from a blindfold game between Ljubomir Ljubojević and Judit Polgár at the 1994 Amber chess tournament.
Black eventually found a winning line, up to a point, but then failed to find 156...Nb4+ and instead tried again to mate in the wrong corner.
In the game Anna Ushenina–Olga Girya, played in the Geneva tournament of the FIDE Women's Grand Prix 2013–2014, White started phase 2 correctly but missed two chances to finish it.
Quickest is to continue the W manoeuvre with Ne5, but White plans to control g8 with knight instead of bishop, which is three moves slower.
After White missed this opportunity, Black can now with best play stave off checkmate long enough for the 50-move draw to come into effect.