How statement and proof provenance work
The first chip identifies the source of the statement or construction; the second identifies the source of its local proof or verification.
- Literature-sourced: the exact statement appears in a cited source; only wording and notation differ.
- AI-adapted: a semantically identical restatement of literature-sourced material, modulo indexing, notation, and boundary cases adopted by the library.
- AI-generated: a genuinely novel statement formulated by AI, with no source for the claim itself.
These labels describe origin, not correctness: citations and verification chips remain separate evidence.
Continuity from below for measures
Statement
Let be an increasing sequence of measurable sets for a measure , so . Then
No finiteness hypothesis is required.
Facts & Assumptions
Given: A measure and measurable sets ; write .
A measure is countably additive on pairwise disjoint measurable sequences (Measures on sigma-algebras).
If are measurable and , then , with the corresponding finite and infinite cases stated explicitly (Measure of a set difference when the smaller set has finite measure).
A nonnegative extended series is the supremum of its finite partial sums (Series in the nonnegative extended real line).
Every subset of has a supremum there (Every subset of has a least upper bound and a greatest lower bound in , agreeing with the real supremum and infimum on nonempty sets bounded in ).
Proof
Define and . The sets are measurable and pairwise disjoint, , and .
Countable additivity gives .
If for some , then by step 1.1 and [L1], while because that value occurs.
If every is finite, then [L2] gives and ; hence the first terms telescope to .
In the finite-valued case, [L3], steps 2.1 and 2.3 give ; step 2.2 gives the same equality in the remaining case, including and a sequence that stabilizes.
Depends on
- Measures on sigma-algebras
- Measure of a set difference when the smaller set has finite measure
- Series in the nonnegative extended real line
- Every subset of $\overline{\mathbb{R}}$ has a least upper bound and a greatest lower bound in $\overline{\mathbb{R}}$, agreeing with the real supremum and infimum on nonempty sets bounded in $\mathbb{R}$
Used by
- Density inversion from an integrable characteristic function Corollary
- A nontight sequence with no probability law subsequence limit Counterexample
- An open dense set of measure less than 1 is the monotone L¹-limit of Riemann integrable indicators, but its indicator is not Riemann integrable Example
- Exponential martingale Brownian tail bound Example
- Green kernel of a biased integer walk Example
- The arctangent distribution function generates a Borel probability measure Example
- A finite-measure measurable set in ℝⁿ has a compact core and a bounded open neighbourhood of arbitrarily small excess Lemma
- A finite-measure measurable set in ℝⁿ is approximable in measure by a finite union of boxes Lemma
- A universal Martin-Löf test exists Lemma
- Approximation in symmetric difference by a generating algebra Lemma
- Assuming countable choice, an infinite-measure set in a semifinite measure space has arbitrarily large finite-measure subsets Lemma
- Basic identities for a probability measure Lemma
- Bounded centered convergent series have summable variances Lemma
- Chacon partial maps extend to an invertible map mod null sets Lemma
- Dyadic coding supplies coin measure and its completed Lebesgue transfer Lemma
- Exact L2 Fourier multiplier norm Lemma
- Finite measures agreeing on a generating pi-system and on the whole space are equal Lemma
- Finite-measure sets are approximable in measure by sets from a countable generating algebra Lemma
- Kolmogorov block polynomial with large partial sums Lemma
- Lipschitz curves and dominated interval vector measures Lemma
- Nondentability produces a vector measure without density Lemma
- Probability algebras, arbitrary joins and the countable chain condition Lemma
- Product rectangle kernels are dense in product L two Lemma
- Real cdf and bounded continuous definitions agree Lemma
- Simultaneous rational conditional distribution function versions Lemma
- Tail comparisons under independent-copy symmetrization Lemma
- The sharp interval bound for Cantor measure Lemma
- Assuming countable choice, the Carathéodory extension dominates every other extension and agrees with it on finite-measure sets Proposition
- Borel cores of sigma-finite Hausdorff measurable sets Proposition
- For sigma-finite measures, the section-measure functions are measurable Proposition
- The Cantor measure is a singular atomless probability measure concentrated on the Cantor set Proposition
- Assuming countable choice, Borel probability measures on Polish spaces are inner regular Theorem
- Assuming countable choice, finite-on-compacts Borel measures on ℝ correspond to nondecreasing right-continuous functions modulo constants Theorem
- Assuming countable choice, Lusin's theorem on finite-measure subsets of Rⁿ Theorem
- Assuming countable choice, regular outer measures are continuous from below on all subsets Theorem
- Assuming countable choice, the Lebesgue measure of a measurable set is the supremum of the measures of its compact subsets Theorem
- Brownian time inversion Theorem
- Continuity from above when one set has finite measure Theorem
- Continuity from below, and from above when one set has finite signed measure Theorem
- Convergence in probability and almost surely agree for independent series Theorem
…and 19 more results.
Dependency tree · two levels
15 results within two dependency steps of this one, each drawn at its shortest distance from it. An arrow runs from a result to what uses it, so the chart reads left to right and ends at this result, which carries a heavier outline. Every node is a link to that result. Click elsewhere on the chart to enlarge it.
Sources
- S. Axler, Measure, Integration & Real Analysis, Theorem 2.59 (standard reference, not scraped)