  This paper deals with the invariance of a measure on Sobolev spaces of low
regularity under the flow of the cubic non linear wave equation on the unit
ball of 3 under the assumption of spherical symmetry. It presents two aspects,
an analytic one which includes the treatment of local properties of the flow,
and a probabilistic one, which is mainly related to the global extension of the
flow and the invariance of the measure.

Analysis of PDEs