We characterize the existence of the solutions of the truncated moments problem in several real variables on unbounded supports by the existence of the maximum of certain concave Lagrangian functions. A natural regularity assumption on the support is required.
Let S be an abelian *-semigroup. In this paper we prove some equivalent conditions for that every positive function is a moment function on S + S + S with a unique representation measure on the set of characters of S.
We find sharp asymptotic estimates for a sequence of exponentials to define a positive definite bilinear form.
We characterize finitely generated abelian semigroups such that every completely positive definite function (a function all of whose shifts are positive definite) is an integral of nonnegative miltiplicative real-valued functions (called nonnegative characters).