Mr. David Cannonier, the head professional at Mahogany Golf Club, must develop a schedule of matches for the couples' golf league that begins its season at 4:00 p.m. tomorrow. Eighteen couples signed up for the league, and each couple must play every other couple over the course of the 17-week season. Mr. Cannonier thought it would be fairly easy to develop a schedule, but after working on it for a couple of hours, he has been unable to come up with a schedule. Because Mr. Cannonier must have a schedule ready by tomorrow afternoon, he has asked you to help him. A possible complication is that one of the couples told Mr. Cannonier that they may have to cancel for the season. They told Mr. Cannonier they would let him know by 1:00 p.m. tomorrow whether they will be able to play this season.