2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/59522A theory of topological gravity is a homotopy-theoretic representation of the Segal-Tillmann topologification of a two-category with cobordisms as morphisms. This note describes a relatively accessible example of such a thing, suggested by the wall-crossing formulas of Donaldson theory.Talk at the RIMS Symposium on algebraic geometry and integrable systems related to string theory, Kyoto, June 12-16, 2000. This final version is to appear in Adv. Theoretical and Mathematical PhysicsDifferential GeometryAlgebraic Topology19Dxx, 57Rxx, 83Cxxtext