"said each branching cascade, where k is an integer greater than a smallest integer j such that 2j is at least as great as a larger of P and Q; and (d) a combining subnetwork of 2???1 combiners for connecting said branching cascade output waveguides of said last branching cascade to said Q switch output waveguides, said branching cascade output waveguides of said last branching cascade being connec" . . . .