We extend Prekopa's Theorem and the Brunn-Minkowski Theorem from convexity to F -subharmonicity. We apply this to the interpolation problem of convex functions and convex sets introducing a new notion of "harmonic interpolation" that we view as a generalization of Minkowski-addition. Contents 1. Introduction 1 2. Background on F -subharmonicity 7 3. Products of Dirichlet Sets 9 4.