%0 Journal Article %T A generalization of Onsager's reciprocity relations to gradient flows with nonlinear mobility %A A. Mielke %A M. A. Peletier %A D. R. M. Renger %J Mathematics %D 2015 %I arXiv %X Onsager's 1931 `reciprocity relations' result connects microscopic time-reversibility with a symmetry property of corresponding macroscopic evolution equations. Among the many consequences is a variational characterization of the macroscopic evolution equation as a gradient-flow, steepest-ascent, or maximal-entropy-production equation. Onsager's original theorem is limited to close-to-equilibrium situations, with a Gaussian invariant measure and a linear macroscopic evolution. In this paper we generalize this result beyond these limitations, and show how the microscopic time-reversibility leads to natural generalized symmetry conditions, which take the form of generalized gradient flows. %U http://arxiv.org/abs/1510.06219v1