Editing Endomorphism (section)

==Operator theory==
In any [[concrete category]], especially for [[vector space]]s, endomorphisms are maps from a set into itself, and may be interpreted as [[unary operator]]s on that set, [[action (group theory)|acting]] on the elements, and allowing the notion of element [[orbit (group theory)|orbit]]s to be defined, etc.

Depending on the additional structure defined for the category at hand ([[topology]], [[metric (mathematics)|metric]], ...), such operators can have properties like [[continuous function (topology)|continuity]], [[Bounded function|boundedness]], and so on.  More details should be found in the article about [[operator theory]].