%0 Journal Article
%T The contraction rate in Thompson metric of order-preserving flows on a cone - application to generalized Riccati equations
%A St¨¦phane Gaubert
%A Zheng Qu
%J Mathematics
%D 2012
%I arXiv
%R 10.1016/j.jde.2014.01.024
%X We give a formula for the Lipschitz constant in Thompson's part metric of any order-preserving flow on the interior of a (possibly infinite dimensional) closed convex pointed cone. This provides an explicit form of a characterization of Nussbaum concerning non order-preserving flows. As an application of this formula, we show that the flow of the generalized Riccati equation arising in stochastic linear quadratic control is a local contraction on the cone of positive definite matrices and characterize its Lipschitz constant by a matrix inequality. We also show that the same flow is no longer a contraction in other natural Finsler metrics on this cone, including the standard invariant Riemannian metric. This is motivated by a series of contraction properties concerning the standard Riccati equation, established by Bougerol, Liverani, Wojtowski, Lawson, Lee and Lim: we show that some of these properties do, and that some other do not, carry over to the generalized Riccati equation.
%U http://arxiv.org/abs/1206.0448v1