English
The topological closure of a star-subalgebra commutes with the star operation, i.e., the star of the closure equals the closure of the star.
Русский
Замыкание звездо-подалгебры коммутирует со звездой: звезда замыкания равна замыканию звезды.
LaTeX
$$"star" of s.topologicalClosure equals (star s).topologicalClosure$$
Lean4
theorem _root_.Subalgebra.topologicalClosure_star_comm (s : Subalgebra R A) :
(star s).topologicalClosure = star s.topologicalClosure :=
by
suffices ∀ t : Subalgebra R A, (star t).topologicalClosure ≤ star t.topologicalClosure from
le_antisymm (this s) (by simpa only [star_star] using Subalgebra.star_mono (this (star s)))
exact fun t =>
(star t).topologicalClosure_minimal (Subalgebra.star_mono subset_closure)
(isClosed_closure.preimage continuous_star)