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Theorems · Theorem · order theory

Topology.IsUpperSet.closure_singleton

∀ {α : Type u_1} [inst : Preorder α] [inst_1 : TopologicalSpace α] [Topology.IsUpperSet α] {a : α},
  closure {a} = Set.Iic a

The closure of a singleton {a} in the upper set topology is the right-closed left-infinite interval $(-∞,a]$.

Defined in
Mathlib.Topology.Order.UpperLowerSetTopology
Cited by
3 results in Mathlib
Foundations
Depth 67 from the axioms · uses propext, Classical.choice, Quot.sound
Assumes
PreorderTopologicalSpaceTopology.IsUpperSet

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