Il gruppo degli automorfismi esterni di un -gruppo nilpotente infinito e suoi -sottogruppi normali
Let be an uncountable universal locally finite group. We study subgroups such that for every , .
Fitting classes and injectors are discussed in the class of -groups. A necessary and sufficient condition for the existence of injectors is given; it is also shown that, when this condition holds, the injectors form a unique conjugacy class.