It is shown how the boson mapping formalism may be applied as a useful
many-body tool to solve a Fermion problem. This is done in the contex
t of generalized Ginocchio models for which we introduce S-, D-, and G
-pairs of fermions and subsequently construct the sdg-boson realizatio
ns of the generalized Dyson type. The constructed S0(12) and Sp(10) fe
rmion models are solved beyond the explicit symmetry limits. Phase tra
nsitions to rotational structures are obtained also in situations wher
e there is no underlying SU(3) symmetry. (C) 1995 Academic Press, Inc.