  We show that each unitary representation of the N=2 superVirasoro algebra can
be realized in terms of ``collective excitations'' over a filled Dirac sea of
fermionic operators satisfying a generalized exclusion principle. These are
semi-infinite forms in the modes of one of the fermionic currents. The
constraints imposed on the fermionic operators have a counterpart in the form
of a model one-dimensional lattice system, studying which allows us to prove
the existence of a remarkable monomial basis in the semi-infinite space. This
leads to a Rogers--Ramanujan-like character formula. We construct the N=2
action on the semi-infinite space using a filtration by finite-dimensional
subspaces (the structure of which is related to the supernomial coefficients);
the main technical tool is provided by the dual functional realization. As an
application, we identify the coinvariants with the dual to a space of
meromorphic functions on products of punctured Riemann surfaces with a
prescribed behaviour on multiple diagonals. For products of punctured $CP^1$,
such spaces are related to the unitary N=2 fusion algebra, for which we also
give an independent derivation.
