Gauged supergravity from dimensional reduction

We perform a generalised Scherk-Schwarz reduction of the effective action of the heterotic string on T-6 to Obtain a massive N = 4 supergravity theory in four dimensions. The local symmetry-group of the resulting d = 4 theory includes a Heisenberg group, which is a subgroup of the global O(6,6 + it) obtained in the standard reduction. We show explicitly that the same theory can be obtained by gauging this Heisenberg group in d = 4,N = 4 supergravity. (C) 1997 Elsevier Science B.V.