Boomer:

I don't get it. What's the difference between your example, and the AAA-BBB-CCC example. Seems to me they are the same. Am I missing something?

AAA = JFK
BBB = LAX
CCC = SAN

Original example, followed by your example:
AAA-BBB, BBB-CCC, CCC-BBB, BBB-AAA
JFK-LAX, LAX-SAN, SAN-LAX, LAX-JFK

Thanks,

Ken Hamer