English
Let A be a nonunital C*-algebra and S be a closed star-subalgebra of A. Then S is a nonunital C*-algebra.
Русский
Пусть A — полная безедв C*-алгебра, и S — замкнутая звезд-подалгебра A. Тогда S является неединичной C*-алгеброй.
LaTeX
$$$NonUnitalCStarAlgebra(A) \wedge S \subseteq A \wedge IsClosed(S) \Rightarrow NonUnitalCStarAlgebra(S)$$$
Lean4
instance nonUnitalCStarAlgebra {S A : Type*} [NonUnitalCStarAlgebra A] [SetLike S A] [NonUnitalSubringClass S A]
[SMulMemClass S ℂ A] [StarMemClass S A] (s : S) [h_closed : IsClosed (s : Set A)] : NonUnitalCStarAlgebra s
where
toCompleteSpace := h_closed.completeSpace_coe
norm_mul_self_le x := CStarRing.norm_star_mul_self (x := (x : A)) |>.symm.le