Tournament Pairing
Tournament pairings can be set in a number of ways. Most are based upon ordering the field of players, before the first game, from strongest to weakest. Once the ordering is set, the field is split into a number of groups based upon prizes to be awarded. Once the groups have been set, the pairings may be determined. There are four primary pairing methods: slaughter, slide, adjacent, and random.
Slaughter pairing (a.k.a. fold)
To perform the pairing, pair the strongest with the weakest player in the group. Repeat by pairing the strongest player with the weakest player from among those that are unpaired till all players have been paired or there is only one player unpaired.
This pairing protects the strongest players, hopefully resulting in these players reaching the semi-finals and finals to produce exciting games at the end of the tournament.
To a large extent, an example of slaughter pairings can be seen in the pairings of the 3rd Toyota Denso Cup. Pairings in that knockout were constrained by considerations of nationality as well as playing strength.
Slide pairing
Done by dividing the group of players, ordered from strongest to weakest, into two strength ordered sets, one containing the stronger players of the group, the other containing the weaker players of the group. The strongest player of the stronger set is paired with the strongest player of the weaker set. The next strongest player of the stronger set is paired with the next strongest player of the weaker set, till all players have been paired or there is only one player unpaired.
Adjacent pairing
To perform the pairing, pair the strongest player with the next strongest, then pair the third strongest with the fourth strongest. Repeat till all players have been paired or there is only one player unpaired.
Rarely used even though they are most likely to produce the largest number of exciting games throughout the tournament.
Random pairing
Chooses the pairs within each group randomly.
In the 2006 US Go Congress, there where groups for each dan grade, as well as each kyu grade of 6 kyu and stronger. From that point down, several kyu grades were combined to form each prize group.
See also: Swiss Pairing, McMahon Pairing, Manual Pairing