We define an equivalence relation on a topological space which is acted by topological monoid as a transformation semigroup. Then, we give some results about the -invariant classes for this relation. We also provide a condition for the existence of relative -invariant classes.
Amin Saif. Adem Kılıçman. "On the -Invariance Property for -Flows." Abstr. Appl. Anal. 2010 1 - 5, 2010. https://doi.org/10.1155/2010/375014