Harmonic synthesis for subgroups
Let be a locally compact group and a closed subgroup. Then is always a set of local spectral synthesis with respect to the algebra , where is the Fourier algebra in the sense of Eymard. Global synthesis holds if and only if a certain condition (C) is satisfied; it is whenever the subgroup is amenable or normal. Global synthesis implies that each convolution operator on with support in which is the ultraweak limit of measures carried by . The problem of passing from local to global...