It seems to me that this is a clear-cut case of Mathematica actually producing the wrong answer (with no warnings).
I'm trying to express the fact that for any integer, there exists a factorization (even if that factorization is just n = n * 1). But Mathematica says no.
If I replace the domain with Reals or Complexes, then it says True.
Is this a bug or am I using these functions incorrectly?
Resolve[ForAll[n, Exists[{p, q}, p*q == n]], Integers]
(*Out[1]= False*)
Reduce[ForAll[n, Exists[{p, q}, p*q == n]], {n, p, q}, Integers]
(*Out[2]= False*)

FullSimplify[ForAll[n, Exists[{p, q}, p*q == n]], {n, p, q} \[Element] Integers]works nicely, though. – J. M.♦ Jul 22 '12 at 19:05FullSimplify[ ForAll[n, Exists[{p, q}, p/Pi q/Sqrt@2 == n]], {n, p, q} \[Element] Integers]– belisarius Jul 22 '12 at 19:16FullSimplify, but rather ofExists/ForAll. E.g.Resolve[ForAll[n, Exists[{p, q}, p*q == n]], {n, p, q} \[Element] Integers]returnsTrue. – Artes Jul 22 '12 at 19:34