Action groupoid
In mathematics, an action groupoid or a transformation groupoid is a groupoid that expresses a group action. Namely, given a group action
we get the groupoid where
- objects are elements of,
- morphisms from to are the actions of elements in such that,
- compositions for and is.
where denote the source and the target of a morphism in ; thus, is the projection and is the given group action.
In an ∞-category
Let be an ∞-category and a groupoid object in it. Then a group action or an action groupoid on an object X in C is the simplicial diagramthat satisfies the axioms similar to an action groupoid in the usual case.