PairingTheory

In a Chess Tournament you'll normally have a Swiss system where the whole field starts off together in one even group. In a Go tournament we use a McMahon system. A McMahon entails dividing the field into lots of little sub groups to start off with. A McMahon tournament with 1 starting group is then the same as a Swiss tournament. How do we pair players? Well we have 4 strategies: simple pairing, fold pairing, split pairing, and adjacent pairing. Before we explain those, let's just say a word about the Bye allocation. In Swiss you'll generally see this done from the middle player. In our McMahon set-up, I took the decision to do it from the bottom player. This is because this way, it should produce a cleaner winner as there is less room for interference with the results above (or near to) the bar. I feel a bit a mean for doing so though, as those poor beginners are getting landed with a bye, and clearly that sucks for them.

Simple Pairing

Here we don't consider tiebreaks or seedings when making a draw. Starting with the top player, we simply pick an opponent from the same MMS group. If none is available, we look in the next group down.

Fold Pairing

Imagine a top group with players in order 1 2 3 4 5 6 7 8. We (literally) fold the group and pair accordingly (1,8) (2,7) (3,6) (4,5). So the top player is always playing the weakest opponent in his group. If there is no valid opponent in his group, we perform the same procedure in the next group down. How do we order the group? Initially with Rating, then by MMS and whichever tiebreakers you chose.

Split Pairing

Imagine a top group with players in order 1 2 3 4 5 6 7 8. We split it into two sections: low and high and pair top low with top high. So we would have (1,5) (2,6) (3,7) (4,8). The wrinkles in the implementation details that follow are then the same as in Fold Pairing.

• odd example of 7 players (1,5) (2,6) (3,7) (4,?)

Adjacent Pairing

Imagine a top group with players in order 1 2 3 4 5 6 7 8. We simply pair adjacent seeds, so (1,2) (3,4) (5,6) (7,8). The wrinkles in the implementation details that follow are then the same as in Fold Pairing.

Ignored

We take absolutely no account of the following:

• the number of handicap stones a game will have.
• the personal or professional relationship of any 2 players.
• the club or country players profess to be from.
• the number of games with white or black that any one player has.