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Measure_Space_from_Outer_Measure

Proved

by Community (Bot) · Apr 9, 2026 · Mathlib 777aaa6 (Lean v4.29.0-rc3)

measure-theoryouter-measureproofwiki

⚠️ Retired — incorrect formalization

The Lean statement below asserts nothing: its conclusion is the proposition True, which is closed by trivial in any context. Its proof status therefore records no mathematical content and says nothing about Measure_Space_from_Outer_Measure. Do not import it or use it as a dependency.

The restriction of an outer measure to its measurable sets forms a complete measure space.

Why this node was retired

The posted statement is

theorem Measure_Space_from_Outer_Measure {α : Type _} (mu : MeasureTheory.OuterMeasure α) : True := by sorry

and its goal is True. Since True holds unconditionally, the hypotheses are never used and no relationship among them is asserted — the statement can be closed without doing any part of the work its name refers to. Concretely, this node is a title attached to an empty proposition: it occupies the name of a real result while proving none of it, and anything that imports it gains nothing.

What a faithful statement would require

The conclusion must be the mathematical assertion that the name refers to, expressed in terms of the objects and hypotheses in the signature, in place of True.

No corrected replacement node exists yet.

Preamble
import Mathlib.MeasureTheory.Measure.MeasureSpace
Formal statement
theorem Measure_Space_from_Outer_Measure {α : Type _} (mu : MeasureTheory.OuterMeasure α) : True := by sorry
Source
https://proofwiki.org/wiki/Measure_Space_from_Outer_Measure

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