this entry is about the concept in group theory; for the concept in quantumfield theory see at effective action functional; for disambiguation see effective action
geometric representation theory
representation, 2-representation, ∞-representation
Grothendieck group, lambda-ring, symmetric function, formal group
principal bundle, torsor, vector bundle, Atiyah Lie algebroid
Eilenberg-Moore category, algebra over an operad, actegory, crossed module
Be?linson-Bernstein localization?
A group action is effective if no group element other than the neutral element acts trivially on all elements of the space.
A group action of a group (group object) $G$ on a set (object) $X$ is effective if $\underset{x \in X}{\forall} g x = x$ implies that $g = e$ is the neutral element.
Beware the similarity to and difference with free action: a free action is effective, but an effective action need not be free.
Last revised on April 14, 2020 at 11:35:14. See the history of this page for a list of all contributions to it.