English
If s is dense, then IsSeparable s is equivalent to SeparableSpace α.
Русский
Если s плотна в пространстве, то IsSeparable s эквивалентно SeparableSpace α.
LaTeX
$$$Dense\ s \Rightarrow (IsSeparable\ s \iff SeparableSpace\ α)$$$
Lean4
theorem _root_.Dense.isSeparable_iff (hs : Dense s) : IsSeparable s ↔ SeparableSpace α := by
simp_rw [IsSeparable, separableSpace_iff, dense_iff_closure_eq, ← univ_subset_iff, ← hs.closure_eq,
isClosed_closure.closure_subset_iff]