Fixing submonoid, fixing subgroup of an action #
In the presence of an action of a monoid or a group, this file defines the fixing submonoid or the fixing subgroup, and relates it to the set of fixed points via a Galois connection.
Main definitions #
Maybe other lemmas are useful
Treat semigroups ?
The Galois connection between fixing submonoids and fixed points of a monoid action
Fixed points of sup of submonoids is intersection
The Galois connection between fixing subgroups and fixed points of a group action