A multi-fermion interaction model is investigated in a compact spacetime with
non-trivial topology and in a weakly curved spacetime. Evaluating the effective
potential in the leading order of the 1/N expansion, we show the phase boundary
for a discrete chiral symmetry in an arbitrary dimensions, 2≤D<4.Comment: 7 pages, 6 figures, Contribution to the proceedings of 2009 Nagoya
Global COE Workshop "Strong Coupling Gauge Theories in LHC Era (SCGT09)