  The appropriate generalization of the isotropic impurity Anderson model for
valence fluctuations between two magnetic multiplets $l^n$ and $l^{n+1}$ is
solved in the strong-coupling limit of Wilson's renormalization group for
$l\leq$ 3. Except in the extreme case of $j-j$ coupling, the ground state is
degenerate, the impurity magnetic moment is very small and is overscreened by
the conduction electrons. The strong-coupling fixed point turns out to be
unstable. Thus, at low enough temperatures the physics of the systems should be
governed by an intermediate coupling fixed point and non Fermi-liquid behavior
is expected.
