Re: [math-fun] Is it me, or is math.stackexchange.com controlled by morons?

Come to think of it, how can we prove that the mapping (0,oo)^3 —> (0,oo)^3 of positive octants via (a,b,c) |—> (girth_ab, girth_bc, girth_ca) is one-to-one? Or is it? —Dan