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.
The modulus of an integral is bounded by the integral of the modulus
Statement
If , then
Facts & Assumptions
Given: An integrable function .
The integral is linear on (The Lebesgue integral is linear on ).
Real and imaginary parts, complex conjugation, and modulus are as in Real and imaginary parts, complex conjugation, and modulus.
Real and complex integrability are defined in Integrable real and complex functions, and their integrals.
The nonnegative integral is monotone (Monotonicity and nonnegative homogeneity of the nonnegative integral).
Proof
For real-valued , the functions and are nonnegative. Therefore [L1] and [L4] give So and hence .
For complex-valued , let . If there is nothing to prove. Otherwise set , so by [L2]. Then and , so step 1.1 applies to the integrable real-valued function . Taking real parts gives because for every complex .
Depends on
Used by
- Linearity, monotonicity, and the modulus bound for expectation Corollary
- One-dimensional W^1,p functions have unique absolutely continuous representatives Corollary
- A step has no locally integrable weak derivative Counterexample
- Cantor function has singular distributional derivative Counterexample
- Strong fractional integration fails at p equal to one Counterexample
- Characteristic function of a real random variable Definition
- The Poisson integral of a finite complex boundary measure Definition
- Dyadic conditional expectation martingale Example
- Interpolation of an averaging operator on a probability space Example
- Newton shell theorem from harmonic mean values Example
- Principal value one over x is tempered and its fourier transform Example
- Uniform laws on expanding finite grids converge to uniform zero one Example
- A Reiter net has an invariant-mean cluster point Lemma
- A topological invariant mean yields norm-approximately invariant densities Lemma
- A UCB-invariant mean yields a topological invariant mean Lemma
- Basic properties of characteristic functions Lemma
- Compact support gives an entire Fourier-Laplace transform by slices Lemma
- Complex l one functionals on finite measure spaces have bounded densities Lemma
- Complex Lq norm recovery from finite simple dual tests Lemma
- Complex translation, convolution, approximate identities, and mollification Lemma
- Distribution pairing with smooth parameter families Lemma
- Fourier-Stieltjes transforms of positive measures are continuous positive definite Lemma
- Gaussian decay gives an entire Fourier-Laplace transform and its growth bound Lemma
- Hedberg pointwise inequality for Riesz potentials Lemma
- L1 convolution smooths bounded functions into UCB Lemma
- Probability-density approximation of continuous tests and topological means Lemma
- Probability-density averages and locally detectable upper essential values Lemma
- Reiter functions can be cut down to Følner sets Lemma
- Schwartz parameter pairing and integral interchange Lemma
- Sigma-finite ergodic oscillation sets have finite measure Lemma
- Submultiplicativity of convolution in the L1 norm Lemma
- The integral transform is representative independent Lemma
- The maximal ergodic inequality on a probability space Lemma
- Compact and locally compact abelian groups are amenable Proposition
- A complex L¹ density defines a complex measure whose total variation is |h| dmu Theorem
- Birkhoff's theorem for an ergodic probability system Theorem
- Complex Holder, Minkowski, and the quotient norm Theorem
- Dominated convergence Theorem
- Far-field asymptotics of compact-source Newtonian potentials Theorem
- Feller converse to Lindeberg-Feller Theorem
…and 14 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
- Gerald B. Folland, Real Analysis, 2nd ed., Proposition 2.22 (standard reference, not scraped)
- John K. Hunter, Measure Theory Notes, Proposition 4.9 (standard reference, not scraped)