English
Using the integer-scalar closure, the same range equality holds with Subring closure.
Русский
С использованием целочисленного замыкания выполняется то же равенство образа.
LaTeX
$$$\mathrm{range}(\mathrm{unitization}(s)) = \mathrm{subalgebraOfSubring}(\mathrm{Subring.closure}(s))$$$
Lean4
theorem starLift_range_le {f : A →⋆ₙₐ[R] C} {S : StarSubalgebra R C} :
(starLift f).range ≤ S ↔ NonUnitalStarAlgHom.range f ≤ S.toNonUnitalStarSubalgebra :=
by
refine ⟨fun h ↦ ?_, fun h ↦ ?_⟩
· rintro - ⟨x, rfl⟩
exact @h (f x) ⟨x, by simp⟩
· rintro - ⟨x, rfl⟩
induction x with
| _ r a => simpa using add_mem (algebraMap_mem S r) (h ⟨a, rfl⟩)