“…To extend pseudo-differential operators to other settings, one observes that the second R n in the Cartesian product R n × R n is the dual of the additive group R n . These observations allow us to extend the definition of pseudo-differential operators to other groups G, provided we have an explicit formula for the dual of G and an explicit Fourier inversion formula on G. Using this approach, the global theory of pseudodifferential operators on other classes of groups, such as S 1 , Z, affine groups, compact (Lie) groups, homogeneous spaces of compact (Lie) groups, Heisenberg groups, graded Lie groups, step two nilpotent Lie groups, and locally compact type I groups has been widely studied by several researchers [8,15,16,4,21,34,23,6,5].…”