Aj. Duran et P. Lopezrodriguez, THE L-P SPACE OF A POSITIVE-DEFINITE MATRIX OF MEASURES AND DENSITY OF MATRIX POLYNOMIALS IN L-1, Journal of approximation theory, 90(2), 1997, pp. 299-318
In this paper we study the space L-p(mu), 1 less than or equal to p le
ss than or equal to + infinity, mu being a positive definite matrix of
measures. We prove that the set of all positive definite matrices of
measures having the same moments as those of mu is compact in the vagu
e topology, and we give a density result for L-1(mu) which is an exten
sion to the matrix case of the classical result for scalar polynomials
and positive measures due to Naimark. (C) 1997 Academic Press.