Covariant Lyapunov Exponents for the Mixmaster
  The dynamics of the Mixmaster Universe is analized in a covariant picture via Misner--Chitre-like variables for an ADM Hamiltonian approach. The system outcomes as isomorphic to a billiard on the Lobachevsky plane and Lyapunov exponents are calculated explicitly. 
Giovanni Imponente and Giovanni Montani