Closure properties for Fitting functors (Q1822615)

Fitting functors have been introduced by \textit{B. Brewster} and the present authors [Math. Z. 182, 359-384 (1983; Zbl 0518.20014)] as a generalization of injectors and radicals for Fitting classes of finite (soluble) groups. This paper provides definitions and properties of certain types of Fitting functors which resemble injectors and radicals for Fitting classes with additional closure properties, most prominently subgroup- or quotient-closed Fitting classes and Fischer classes.