Abstract

ABSTRACT In this paper we present a universal solution to the generalized moment problem, with a nonclassical complexity constraint. We show that this solution can be obtained by minimizing a strictly convex nonlinear functional. This optimization problem is derived in two different ways. We first derive this intrinsically, in a geometric way, by path integration of a one-form which defines the generalized moment problem. It is observed that this one-form is closed and defined on a convex set, and thus exact with, perhaps surprisingly, a strictly convex primitive function. We also derive this convex functional as the dual problem of a problem to maximize a cross entropy functional. In particular, these approaches give a constructive parameterization of all solutions to the Nevanlinna-Pick interpolation problem, with possible higher-order interpolation at certain points in the complex plane, with a degree constraint as well as all soutions to the rational covariance extension problem- two areas which have been advanced by the work of Hidenori Kimura. Illustrations of these results in system identifiaction and probablity are also mentioned. Key words. Moment problems, convex optimization, Nevanlinna-Pick interpolation, covariance extension, systems identification, Kullback-Leibler distance. 1

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