Programming puzzles: processing lists!

[DavidM]

#37 may be more complicated than it first appears. While the 4-team example is fairly straightforward, I need some clarification on the problem for larger team counts.

Let's say you have 6 teams. One possible set of pairings is:

1-2 3-4 5-6

Unlike the case of a 4-team scenario, however, there's the possibility of multiple match-days that still share a common match. Using the above example, here's three potential match-days that all have a 5-6 match:

1-2 3-4 5-6
1-3 2-4 5-6
2-3 1-4 5-6

My question is: should the output include all three of these as match-days? If not, which is the "correct" one, and what makes it so?