If Yale beats Brown and Cornell beats Columbia, then it is complicated. I haven't looked at the tie breakers. Yale gets #1 in that scenario and the league title is split 2 ways. Brown wins, then they are #4, and the Penn princeton winner geys the title and #1.
Edit - I think if Brown loses to Yale, then Cornell gets in with a tie because Cornell split with the top seed and brown would have lost twice. Brown wins or Cornell loses, brown is in.