Loading AI tools
From Wikipedia, the free encyclopedia
In group theory, a branch of mathematics, Frattini's argument is an important lemma in the structure theory of finite groups. It is named after Giovanni Frattini, who used it in a paper from 1885 when defining the Frattini subgroup of a group. The argument was taken by Frattini, as he himself admits, from a paper of Alfredo Capelli dated 1884.[1]
This article has multiple issues. Please help improve it or discuss these issues on the talk page. (Learn how and when to remove these messages)
|
If is a finite group with normal subgroup , and if is a Sylow p-subgroup of , then
where denotes the normalizer of in , and means the product of group subsets.
The group is a Sylow -subgroup of , so every Sylow -subgroup of is an -conjugate of , that is, it is of the form for some (see Sylow theorems). Let be any element of . Since is normal in , the subgroup is contained in . This means that is a Sylow -subgroup of . Then, by the above, it must be -conjugate to : that is, for some
and so
Thus
and therefore . But was arbitrary, and so
Seamless Wikipedia browsing. On steroids.
Every time you click a link to Wikipedia, Wiktionary or Wikiquote in your browser's search results, it will show the modern Wikiwand interface.
Wikiwand extension is a five stars, simple, with minimum permission required to keep your browsing private, safe and transparent.