Clifford Theory for Group Representations

Let N be a normal subgroup of a finite group G and let F be a field. An important method for constructing irreducible FG-modules consists of the application (perhaps repeated) of three basic operations: (i) restriction to FN. (ii) extension from FN. (iii) induction from FN. This is the `Clifford Theory'' developed by Clifford in 1937. In the past twenty years, the theory has enjoyed a period of vi...