Re: [math-fun] Rational Group

= Jon Perry {Q,+} (the rationals with the addition operator) is a group. How come the infinite sum of rationals is not then necessarily a member of this group, e.g. zeta(2)?

A quick answer would be that while all finite summations can be inductively shown to be covered by the group axioms (specifically, closure) infinite summation has to introduce an additional new concept, namely the limit of an infinite sequence (specifically, of finite sums), which is not.