FROM SUM-RULES TO RPA .1. NUCLEI

We take up the flexible formulation of RPA in subspaces of coordinate-like and momentum-like 1 ph operators which was developed in the preceeding paper. We draw the connection to many of the known collective approximations to RPA by proper choice of the subspace of operators. We finally apply the newly developed scheme to comparative studies of a hierarchy of approaches for the RPA spectra of doubly magic nuclei described with Skyrme forces.