  We define a hierarchy of dynamic relaxed gas spheres as solutions of the
Poisson equation coupled to a hierarchy of approximations of the Liouville
equation leading, when this equation is satisfied, to the well-known isothermal
gas spheres in the static case, but also to a new form of dynamic maximum
relaxation. The two previous steps of the hierarchy correspond to an increasing
degree of local relaxation at the center of the configuration.

General Relativity and Quantum Cosmology