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feat: TotallySeparatedSpace instance for profinite sets (#6722)
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Adds an instance `TotallySeparatedSpace` for totally disconnected compact Hausdorff spaces. This direction of `compact_t2_tot_disc_iff_tot_sep` was missing an instance.
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dagurtomas committed Aug 23, 2023
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3 changes: 3 additions & 0 deletions Mathlib/Topology/Separation.lean
Expand Up @@ -1984,6 +1984,9 @@ theorem compact_t2_tot_disc_iff_tot_sep : TotallyDisconnectedSpace α ↔ Totall

variable [TotallyDisconnectedSpace α]

/-- A totally disconnected compact Hausdorff space is totally separated. -/
instance : TotallySeparatedSpace α := compact_t2_tot_disc_iff_tot_sep.mp inferInstance

theorem nhds_basis_clopen (x : α) : (𝓝 x).HasBasis (fun s : Set α => x ∈ s ∧ IsClopen s) id :=
fun U => by
constructor
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