TheoremBase

The Borel Sets of ℝⁿ, Lebesgue Measure on ℝⁿ and Integrals against It Are Predicative in the Dimension

The conditions that a set is the Borel σ-algebra of ℝⁿ, that a set is Lebesgue measure on ℝⁿ, and that a number is the integral of a nonnegative measurable function against Lebesgue measure on ℝⁿ, are expressed by predicative formulas in which the dimension n is a variable; so inductions on the dimension may use them.

Statement

In the setting of Product Measures and Lebesgue Measure on ℝⁿ: Standing Notation and Background, assume the axiom of dependent choice; this item is a statement of the metatheory. Let N≥1N\ge1 be a metatheoretic number, let x0,…,xN−1x_{0},\dots,x_{N-1} be distinct set variables, and let i,j,k<Ni,j,k<N, not necessarily distinct. Each clause states that a condition on x0,…,xN−1x_{0},\dots,x_{N-1} is predicative: expressed by a predicative formula, with x0,…,xN−1x_{0},\dots,x_{N-1} in place of the variables of Conditions Expressed by a Predicative Formula, and Guards (i) and no displayed variables. The other letters, among them the sets of numbers and [0,∞][0,\infty] with their operations and orders, are parameters. For n∈Nn\in\mathbb{N}, Rn\mathbb{R}^{n} is Euclidean space, B(Rn)\mathcal{B}(\mathbb{R}^{n}) its Borel σ\sigma-algebra, λn\lambda_{n} Lebesgue measure on Rn\mathbb{R}^{n}, and M+(Rn,B(Rn))\mathcal{M}^{+}(\mathbb{R}^{n},\mathcal{B}(\mathbb{R}^{n})) and ∫Rng dλn\int_{\mathbb{R}^{n}}g\,d\lambda_{n} are as in the setting.

Borel sets. With n=xin=x_{i} and G=xj\mathcal{G}=x_{j}: "n∈Nn\in\mathbb{N} and G=B(Rn)\mathcal{G}=\mathcal{B}(\mathbb{R}^{n})".

Lebesgue measure. With n=xin=x_{i} and κ=xj\kappa=x_{j}: "n∈Nn\in\mathbb{N} and κ=λn\kappa=\lambda_{n}".

Integrals against Lebesgue measure. With n=xin=x_{i}, g=xjg=x_{j} and r=xkr=x_{k}: "n∈Nn\in\mathbb{N}, g∈M+(Rn,B(Rn))g\in\mathcal{M}^{+}(\mathbb{R}^{n},\mathcal{B}(\mathbb{R}^{n})) and r=∫Rng dλnr=\int_{\mathbb{R}^{n}}g\,d\lambda_{n}".

Proofs

Log in to submit a proof.

Loading...

Citations

Loading…

Dependencies

Loading…

Related

0 relations

Curated associations between results. These are editable and subjective — they do not replace the dependency graph, which is derived from the references in the text.

No relations recorded yet.

Comments

Log in to comment.

Loading…