The e-address of Roger Hindley has changed to j.r.hindley@swansea.ac.uk (Former address majrh@pyramid.swansea.ac.uk will be working for a few weeks more, but the Pyramid machine will probably die soon.) Roger Hindley, Mathematics Dept., University College of Swansea, Wales, U.K. SA2 8PP Tel. (+) 44-792-205678 ext. 4624 Fax (+) 44-792-295843