Permuting subgroups

This article defines a symmetric relation on the collection of subgroups inside the same group.

Definition

Definition with symbols

Two subgroups $H$ and $K$ of a group $G$ are termed permuting subgroups if the following equivalent conditions hold:

• $HK=KH$
• $HK$ (the product) is a subgroup
• Given elements $h$ in $H$ and $k$ in $K$, there exist elements $k'$ in $K$ and $h'$ in $H$ such that $hk=k'h'$.

Relation with other relations

Stronger relations

• One is a normalizing subgroup for the other
• Mutually permuting subgroups
• Totally permuting subgroups
• Conjugate-permuting subgroups

Weaker relations

• Elliptic pair of subgroups