The geodesic flow of a generic metric does not admit nontrivial integrals polynomial in momenta

Abstract

Any smooth geodesic flow is locally Liouville integrable with smooth integrals. We show that generically this fails if we require, in addition, that the integrals are polynomial (or, more generally, analytic) in momenta. Consequently we obtain that a generic real-analytic metric does not admit, even locally, a real-analytic integral.