On Bosonic and Supersymmetric Current Algebras for Non-Semi-Simple Groups

We present a systematic approach to constructing current algebras based on non-semi-simple groups. The Virasoro central charges corresponding to these current algebras are not, in general, given by integer numbers. The key point in this construction is that the bilinear form appearing in the current algebra can be different from the bilinear form used to raise and lower group indices. The action which realises this current algebra as its symmetry is also found.