The generalised geometry of type II non-geometric fluxes under T and S dualities

We examine the flux structures defined by NS-NS superpotentials of Type IIA and Type IIB string theories compactified on a particular class of internal spaces which include non-geometric flux contributions due to T duality or mirror symmetry. This is then extended to the Type IIB R-R sector through the use of S duality and then finally to its mirror dual Type IIA R-R sector, with note of how this sector breaks S duality invariance in Type IIA. The nilpotency and tadpole constraints associated with the fluxes induced by both dualities are derived, explicitly demonstrated to be mirror invariant and classified in terms of S duality multiplets. These results are then used to motivate the postulation of an additional symmetry for internal spaces which are their own mirror duals and an analysis is done of the resultant constraints for such a construction.