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.
Measures on sigma-algebras
Definition
Let be a set and let be a sigma-algebra on (Sigma-algebras). A measure on is a function
such that:
- ;
- for every pairwise disjoint sequence in , where the right side is the nonnegative extended sum of Series in the nonnegative extended real line.
The second condition is countable additivity. It begins at index and includes the case in which some term or the total sum is .
Depends on
Used by
- Every subset of ℝ of positive Lebesgue outer measure contains a nonmeasurable subset Corollary
- Polar integration may discard the cut locus Corollary
- The Solovay model has no Vitali or Bernstein set Corollary
- A non-sigma-finite premeasure has distinct Borel extensions Counterexample
- No normalized translation-invariant Haar probability on the real line Counterexample
- The zero-countable / infinity-cocountable measure space breaks the p=1 endpoint of duality Counterexample
- A Borel measure on ℝ that is finite on compact sets Definition
- A positive, signed, or complex measure concentrated on a measurable set Definition
- Absolute continuity of a signed or complex measure with respect to a positive measure Definition
- An atom of a measure on ℝ Definition
- Banach-valued vector measure and variation Definition
- Borel master codes for null and meagre sets Definition
- Finite, sigma-finite, and semifinite measures Definition
- Measure kernel and probability kernel Definition
- Measure spaces Definition
- Nonnegative scalar multiples and countable weighted sums of measures Definition
- PMEA and PMEA-sigma Definition
- Probability measures and probability spaces Definition
- Radon measure on an LCH space Definition
- Restriction of a measure to a measurable set Definition
- Support of a finite Borel measure on the plane Definition
- The distribution function of absolute value Definition
- The integral of a nonnegative simple function Definition
- The one-dimensional torus and its normalized Haar integral Definition
- A boundary atom gives an h1 function without an L1 density Example
- A square-integrable kernel without a continuous representative Example
- Arcsine equilibrium measure and capacity of a segment Example
- Assuming countable choice, zero on countable sets and infinity on cocountable sets is a non-semifinite measure Example
- Green kernel of a biased integer walk Example
- Isotypic Haar projections specialize to finite character sums Example
- Negative drift gives a finite mean small-set hit Example
- Weighted counting in dimension zero Example
- FALSE: a measure on an infinite set that vanishes on every singleton is the zero measure False statement
- FALSE: every finitely additive nonnegative function on an algebra extends to a measure False statement
- FALSE: every finitely additive nonnegative set function on a sigma-algebra is a measure False statement
- FALSE: every subset of a measure-null set is measurable False statement
- FALSE: measures are additive on arbitrary countable unions False statement
- FALSE: the extension of a premeasure is always unique False statement
- A measurable set of positive finite measure occupies more than any prescribed proportion of some dyadic cube Lemma
- A shear sends the unit cube to a set of Lebesgue measure one Lemma
…and 51 more results.
Dependency tree · two levels
12 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, §2C (standard reference, not scraped)
- G. Folland, Real Analysis, 2nd ed., §1.3 (standard reference, not scraped)