  In this paper, we carry out a new technique named projection ED and indicate
that it is applicable to the frustrated models, e.g., XXZ spin-1/2 Heisenberg
and spinless fermion t-V models, in the strong coupling limit with highly
degenerate ground states in a general way. As an example, we deal with a
spinless fermion t-V model on a triangular lattice and show the usefulness of
the method.
