Abstract

In this talk we discuss the complete classification of half-supersymmetric branes in toroidally compactified IIA /IIB string theory in terms of representations of the T-duality group. We show that the branes of ten-dimensional IIA /IIB string theory must satisfy, upon toroidal compactification, specific wrapping rules in order to reproduce the number of supersymmetric branes in lower dimensions. The realisation of these wrapping rules suggests that IIA /IIB string theory contains a whole class of generalised Kaluza-Klein monopoles. We find examples of T-duality representations of branes in lower dimensions, suggested by supergravity, of which none of the component branes follow from the reduction of any brane in ten-dimensional IIA /IIB string theory.