  Brylawski's tensor product formula expresses the Tutte polynomial of the
tensor product of two graphs in terms of Tutte polynomials arising from the
tensor factors. We are concerned with extensions of Brylawski's tensor product
formula to the Bollobas-Riordan and transition polynomials of graphs embedded
in surfaces. We give a tensor product formula for the multimatroid transition
polynomial and show that Brylawski's formula and its topological analogues
arise as specialisations of this more general result.
