# PlanetPhysics/Groupoid Action

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LetFailed to parse (unknown function "\grp"): {\displaystyle \grp}be a groupoid and a topological space. Agroupoid action, orFailed to parse (unknown function "\grp"): {\displaystyle \grp}-action, on is given by two maps: theanchor mapand a map with the latter being defined on pairs such that , written as . The two maps are subject to the following conditions:

- and
- whenever the operations are defined.

{\mathbf Note:} The groupoid action generalizes the concept of group action in a non-trivial way