We define a sequence of microscopic dynamical variables by decomposing a Hilbert space into orthogonal subspaces, and construct for them a new hierarchy of equations which is particularly useful for highly correlated systems. A formal solution is shown to give a microscopic expression of Mori's...

A new formula for the binary collision expansion of the unitary operator U (t2, t1) is proposed. The formula is applied to the expansion of the partial Green's functions of Kadanoff-Baym in powers of the correct binary scattering amplitude. It is shown that certain linked diagrams of...