I'm just started lecture myself about arrow's theorem. There are some problems which make me confused.ARROW'S THEOREM: Any constitution that respects transitivity, independence of irrelevant alternatives, and unanimity is a dictatorship.This is a kind of statement from john Geanakoplos' paper. I think unanimity+transitivity and independence of irrelevant alternatives are equivalent. For example:voter A: a>b>c>dvoter B: a>c>b>dvoter C: a>d>c>bSo we can conclude that everybody prefers a to b just according to unanimity and transitivity. And I think this conclusion implies independence of irrelevant alternatives. So if I drop the constraint of independence of irrelevant alternatives, Is this still right?
Some problems about arrow's theorem and social choice
gt.game theory;social sciences