Re: [math-fun] The Axiom of Choice for roots of z^2 + 1

Well, 1 and -1 have different algebraic properties. E.g., 1 is the unique complex number whose product with any other number z is z. -1 is the unique complex number that's unequal to 1 but whose square is 1.

Thanks Dan and Joshua. That's what I get for being ignorant--I learn stuff. :-) Kerry