Massive T-duality in six dimensions

A massive version of T-duality in six dimensions is given, that maps the K3 compactification of Romans' theory onto the K3 compactification of type II B theory. This is done by performing a (standard) Kaluza-Klein reduction on six-dimensional massive type IIA and a Scherk-Schwarz reduction on type II B, mapping both theories onto the same five-dimensional theory. We also com ment shortly on the difficulties arising if one intends to construct a mass ive generalisation of the six-dimensional string-string duality. (C) 2001 E lsevier Science B.V. All rights reserved.