Algebraic theory of affine curvature tensors
  We use curvature decompositions to construct generating sets for the space of algebraic curvature tensors and for the space of tensors with the same symmetries as those of a torsion free, Ricci symmetric connection; the latter naturally appear in relative hypersurface theory. 
N. Blazic, P. Gilkey, S. Nikcevic, and U. Simon