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Mathlib.MeasureTheory.Function.LpSpace.DomAct.Continuous

Continuity of the action of Mᵈᵐᵃ on MeasureSpace.Lp E p μ #

In this file we prove that under certain conditions, the action of Mᵈᵐᵃ on MeasureTheory.Lp E p μ is continuous in both variables.

Recall that Mᵈᵐᵃ acts on MeasureTheory.Lp E p μ by mk c • f = MeasureTheory.Lp.compMeasurePreserving (c • ·) _ f. This action is defined, if M acts on X by mesaure preserving maps.

If M acts on X by continuous maps preserving a locally finite measure which is inner regular for finite measure sets with respect to compact sets, then the action of Mᵈᵐᵃ on Lp E p μ described above, 1 ≤ p < ∞, is continuous in both arguments.

In particular, it applies to the case when X = M is a locally compact topological group, and μ is the Haar measure.

Tags #

measure theory, group action, domain action, continuous action, Lp space