Interpolation sets and the size of quotients of function spaces on a\n locally compact group

We devise a fairly general method for estimating the size of quotients\nbetween algebras of functions on a locally compact group. This method is based\non the concept of interpolation sets and unifies the approaches followed by\nmany authors to obtain particular cases.\n Among the applications we find, we obtain that the quotients WAP(G)/B(G) (G\nbeing a locally compact group in the class [IN] or a nilpotent locally compact\ngroup) and CB(G)/LUC(G) (G being any non-compact non-discrete locally compact\ngroup) contain a linearly isometric copy of \\ell_\\infty(\\kappa(G)) where\n\\kappa(G) is the compact covering number of G, and WAP(G), B(G) and LUC(G)\nrefer, respectively, to the algebra of weakly almost periodic functions, the\nuniform closure of the Fourier-Stieltjes algebra and the bounded right\nuniformly continuous functions.\n