Let P be the set of primes, and let Q_p and Z_p(t) be the fields of p-adic numbers and formal power series over Z_p = (0, 1, ..., p - 1). Further, suppose that D is a "nonprincipal maximal filter" on P. Then product_(p element P) Q_p/D and product_(p element P) Z_p(t)/D are isomorphic.

hyperreal number | nonstandard analysis