USE OF LIE SYMMETRIES AND THE PAINLEVÉ ANALYSIS IN COSMOLOGY

Abstract

Two techniques for the analysis of differential equations, the Lie method of extended groups and the Painlevé analysis, are reviewed. The implications for integrability in the case of the existence of symmetries in the former or the possession of the Painlevé property in the latter are explored. By way of an example an equation which arises in shear-free flow of a spherically symmetric perfect fluid with conformal symmetry in general relativity is given an extensive treatment with both techniques.