HYPERSURFACE HOMOGENEOUS AND HYPERSURFACE SELF-SIMILAR MODELS

Dynamical systems for hypersurface homogeneous and hypersurface self-s imilar models with non-null symmetry surfaces are derived. The equatio ns are cast in a geometric form based on properties of the symmetry su rfaces that emphasize the close connection between the various models. Perfect fluid models are discussed in particular. It is shown how the models form a hierarchical structure where simpler models act as buil ding blocks for more complicated ones. Expressions for the fluid's kin ematic properties are given and discussed in the context of various sp ecial cases.