# Contents

## Idea

An involution is an endomorphism whose square is the identity morphism. Such an endomorphism must be an automorphism; indeed, it is its own inverse.

Where this makes sense, an anti-involution is an antihomomorphism instead of a homomorphism (so an antiendomorphism and necessarily an antiautomorphism).

Revised on February 27, 2014 08:35:57 by Urs Schreiber (82.113.98.143)