Integrability by quadratures for systems of involutive vector fields

Abstract

Starting from results and ideas of S. Lie anb E. Cartan, we give a systematic and geometric treatment of integrability dy quadratures of involutive systems of vector filds, showing how-a-generalization of the usual multiplier can-de constructed with the aid of closed differential forms and enough symmetry vector fields. This leads us to explicit formulas for the indepen-. dent integrals. These results allow us to identify symmetries with integral invariants in the sense of Poincare and Cartan. A further (new) result gives the equivalence of integrability by quadratures and the existence of solvable structures, these latter being generalizations. of solvable algebras.