Here is more info: http://www.ai.mit.edu/courses/6.034f/psets/ps1/airtravel.pdf http://www.ai.mit.edu/courses/6.034f/psets/ps1/airtravel.pdf It's from 2003, th

Here is more info: http://www.ai.mit.edu/courses/6.034f/psets/ps1/airtravel.pdf http://www.ai.mit.edu/courses/6.034f/psets/ps1/airtravel.pdf It's from 2003, thing got a lot worse since then. The carriers make the rule mechanisms without having mathematicians or computer scientists at hand that watch the combinatorics. They have enough trouble not misfiling fares altogether (aka $0.02 fare NYC->London next Friday).