(p, q)-John Ellipsoids

Abstract

As an extension of the classical John ellipsoid and the $$L_{p}$$ -John ellipsoids due to Lutwak–Yang–Zhang, this paper studies (p, q)-John ellipsoids. We consider an optimization problem about the (p, q)-mixed volumes, whose solution is uniquely existed for all $$0<p\le q$$ . The solution allows us to introduce the concept of (p, q)-John ellipsoids. As applications, we established an analog of the John’s inclusion theorem and Ball’s volume-ratio inequality for (p, q)-John ellipsoids. Moreover, the connection between the isotropy of measures and the characterization of (p, q)-John ellipsoids is demonstrated.