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Viewing Version 6 of '$p$-group'
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Title of object: $p$-group
Canonical Name: PGroup4
Type: Definition

Created on: 2004-12-12 10:56:47
Modified on: 2005-11-25 17:42:04

Creator: yark
Modifier: yark
Author: yark

Classification: msc:20F50
Defines: p-subgroup, primary component
Synonyms: $p$-group=p-group

Revision comment (for changes between this and next version):

see also

Preamble:

\usepackage{amssymb}
\usepackage{amsmath}
\usepackage{amsfonts}
Content:

\PMlinkescapeword{component}
\PMlinkescapeword{maximal}
\PMlinkescapeword{subgroup}


Let $p$ be a prime number.
A \emph{$p$-group} is a group in which the order of every element is a power of $p$.
A \PMlinkname{subgroup}{Subgroup} that is itself a $p$-group is called a \emph{$p$-subgroup}.

Using Lagrange's Theorem and Cauchy's Theorem one may show that a finite group $G$ is a $p$-group if and only if $|G|$ is a power of $p$.

It follows from Zorn's Lemma that every group has a maximal $p$-subgroup, for every prime $p$. The maximal $p$-subgroup need not be unique (though for abelian groups it is always unique, and is called the \emph{$p$-primary component} of the abelian group). A maximal $p$-subgroup may, of course, be trivial. Non-trivial maximal $p$-subgroups of finite groups are called \PMlinkname{Sylow $p$-subgroups}{SylowPSubgroups}.