[math-fun] P.S. Re: Biijection between the sets of even and odd subsets of an even-sized set

P.S. I meant to mention that someone else brought up this example in math-fun some years ago. But I don't recall knowing exactly what "natural" meant in this context. --Dan _____________________________________________________________________ "It don't mean a thing if it ain't got that certain je ne sais quoi." --Peter Schickele