ultrafilter_isOpen_basic

∀ {α : Type u} (s : Set α), IsOpen {u | s ∈ u}

The basic open sets for the topology on ultrafilters are open.

Defined in: Mathlib.Topology.Compactification.StoneCech
Cited by: 5 results in Mathlib
Foundations: Depth 62 from the axioms · uses propext, Classical.choice, Quot.sound

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