McMahon is a tournament pairing system devised by Lee McMahon many years ago. Details and discussion on this may be found in Sensei's library.
- Each player enters at a grade which is converted to a McMahon score: X kyu -> -X and Y dan -> Y-1 except for players above the bar who are all treated as if they are the grade of the bar
- In each round, pairings are made between players of (approximately) the same McMahon score.
- At the end of each round, the winners score is increased by 1. (Jigo increases both by 0.5, as does a bye (a round not played by agreement with the organisers)).
- The winner is the player with the highest final score. (See the results table of one such tournament).