Matter collineations: The inverse ‘‘symmetry inheritance’’ problem

Matter collineations, as a symmetry property of the energy-momentum tensor Tab, are studied from the point of view of the Lie algebra of vector fields generating them. Most attention is given to space–times with a degenerate energy-momentum tensor. Some examples of matter collineations are found for dust fluids (including Szekeres’s space–times), and null fluid space–times.