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| Type | Label | Description |
|---|---|---|
| Statement | ||
| Theorem | isrnmeas 34201* | The property of being a measure on an undefined base sigma-algebra. (Contributed by Thierry Arnoux, 25-Dec-2016.) |
| ⊢ (𝑀 ∈ ∪ ran measures → (dom 𝑀 ∈ ∪ ran sigAlgebra ∧ (𝑀:dom 𝑀⟶(0[,]+∞) ∧ (𝑀‘∅) = 0 ∧ ∀𝑥 ∈ 𝒫 dom 𝑀((𝑥 ≼ ω ∧ Disj 𝑦 ∈ 𝑥 𝑦) → (𝑀‘∪ 𝑥) = Σ*𝑦 ∈ 𝑥(𝑀‘𝑦))))) | ||
| Theorem | dmmeas 34202 | The domain of a measure is a sigma-algebra. (Contributed by Thierry Arnoux, 19-Feb-2018.) |
| ⊢ (𝑀 ∈ ∪ ran measures → dom 𝑀 ∈ ∪ ran sigAlgebra) | ||
| Theorem | measbasedom 34203 | The base set of a measure is its domain. (Contributed by Thierry Arnoux, 25-Dec-2016.) |
| ⊢ (𝑀 ∈ ∪ ran measures ↔ 𝑀 ∈ (measures‘dom 𝑀)) | ||
| Theorem | measfrge0 34204 | A measure is a function over its base to the positive extended reals. (Contributed by Thierry Arnoux, 26-Dec-2016.) |
| ⊢ (𝑀 ∈ (measures‘𝑆) → 𝑀:𝑆⟶(0[,]+∞)) | ||
| Theorem | measfn 34205 | A measure is a function on its base sigma-algebra. (Contributed by Thierry Arnoux, 13-Feb-2017.) |
| ⊢ (𝑀 ∈ (measures‘𝑆) → 𝑀 Fn 𝑆) | ||
| Theorem | measvxrge0 34206 | The values of a measure are positive extended reals. (Contributed by Thierry Arnoux, 26-Dec-2016.) |
| ⊢ ((𝑀 ∈ (measures‘𝑆) ∧ 𝐴 ∈ 𝑆) → (𝑀‘𝐴) ∈ (0[,]+∞)) | ||
| Theorem | measvnul 34207 | The measure of the empty set is always zero. (Contributed by Thierry Arnoux, 26-Dec-2016.) |
| ⊢ (𝑀 ∈ (measures‘𝑆) → (𝑀‘∅) = 0) | ||
| Theorem | measge0 34208 | A measure is nonnegative. (Contributed by Thierry Arnoux, 9-Mar-2018.) |
| ⊢ ((𝑀 ∈ (measures‘𝑆) ∧ 𝐴 ∈ 𝑆) → 0 ≤ (𝑀‘𝐴)) | ||
| Theorem | measle0 34209 | If the measure of a given set is bounded by zero, it is zero. (Contributed by Thierry Arnoux, 20-Oct-2017.) |
| ⊢ ((𝑀 ∈ (measures‘𝑆) ∧ 𝐴 ∈ 𝑆 ∧ (𝑀‘𝐴) ≤ 0) → (𝑀‘𝐴) = 0) | ||
| Theorem | measvun 34210* | The measure of a countable disjoint union is the sum of the measures. (Contributed by Thierry Arnoux, 26-Dec-2016.) |
| ⊢ ((𝑀 ∈ (measures‘𝑆) ∧ 𝐴 ∈ 𝒫 𝑆 ∧ (𝐴 ≼ ω ∧ Disj 𝑥 ∈ 𝐴 𝑥)) → (𝑀‘∪ 𝐴) = Σ*𝑥 ∈ 𝐴(𝑀‘𝑥)) | ||
| Theorem | measxun2 34211 | The measure the union of two complementary sets is the sum of their measures. (Contributed by Thierry Arnoux, 10-Mar-2017.) |
| ⊢ ((𝑀 ∈ (measures‘𝑆) ∧ (𝐴 ∈ 𝑆 ∧ 𝐵 ∈ 𝑆) ∧ 𝐵 ⊆ 𝐴) → (𝑀‘𝐴) = ((𝑀‘𝐵) +𝑒 (𝑀‘(𝐴 ∖ 𝐵)))) | ||
| Theorem | measun 34212 | The measure the union of two disjoint sets is the sum of their measures. (Contributed by Thierry Arnoux, 10-Mar-2017.) |
| ⊢ ((𝑀 ∈ (measures‘𝑆) ∧ (𝐴 ∈ 𝑆 ∧ 𝐵 ∈ 𝑆) ∧ (𝐴 ∩ 𝐵) = ∅) → (𝑀‘(𝐴 ∪ 𝐵)) = ((𝑀‘𝐴) +𝑒 (𝑀‘𝐵))) | ||
| Theorem | measvunilem 34213* | Lemma for measvuni 34215. (Contributed by Thierry Arnoux, 7-Feb-2017.) (Revised by Thierry Arnoux, 19-Feb-2017.) (Revised by Thierry Arnoux, 6-Mar-2017.) |
| ⊢ Ⅎ𝑥𝐴 ⇒ ⊢ ((𝑀 ∈ (measures‘𝑆) ∧ ∀𝑥 ∈ 𝐴 𝐵 ∈ (𝑆 ∖ {∅}) ∧ (𝐴 ≼ ω ∧ Disj 𝑥 ∈ 𝐴 𝐵)) → (𝑀‘∪ 𝑥 ∈ 𝐴 𝐵) = Σ*𝑥 ∈ 𝐴(𝑀‘𝐵)) | ||
| Theorem | measvunilem0 34214* | Lemma for measvuni 34215. (Contributed by Thierry Arnoux, 6-Mar-2017.) |
| ⊢ Ⅎ𝑥𝐴 ⇒ ⊢ ((𝑀 ∈ (measures‘𝑆) ∧ ∀𝑥 ∈ 𝐴 𝐵 ∈ {∅} ∧ (𝐴 ≼ ω ∧ Disj 𝑥 ∈ 𝐴 𝐵)) → (𝑀‘∪ 𝑥 ∈ 𝐴 𝐵) = Σ*𝑥 ∈ 𝐴(𝑀‘𝐵)) | ||
| Theorem | measvuni 34215* | The measure of a countable disjoint union is the sum of the measures. This theorem uses a collection rather than a set of subsets of 𝑆. (Contributed by Thierry Arnoux, 7-Mar-2017.) |
| ⊢ ((𝑀 ∈ (measures‘𝑆) ∧ ∀𝑥 ∈ 𝐴 𝐵 ∈ 𝑆 ∧ (𝐴 ≼ ω ∧ Disj 𝑥 ∈ 𝐴 𝐵)) → (𝑀‘∪ 𝑥 ∈ 𝐴 𝐵) = Σ*𝑥 ∈ 𝐴(𝑀‘𝐵)) | ||
| Theorem | measssd 34216 | A measure is monotone with respect to set inclusion. (Contributed by Thierry Arnoux, 28-Dec-2016.) |
| ⊢ (𝜑 → 𝑀 ∈ (measures‘𝑆)) & ⊢ (𝜑 → 𝐴 ∈ 𝑆) & ⊢ (𝜑 → 𝐵 ∈ 𝑆) & ⊢ (𝜑 → 𝐴 ⊆ 𝐵) ⇒ ⊢ (𝜑 → (𝑀‘𝐴) ≤ (𝑀‘𝐵)) | ||
| Theorem | measunl 34217 | A measure is sub-additive with respect to union. (Contributed by Thierry Arnoux, 20-Oct-2017.) |
| ⊢ (𝜑 → 𝑀 ∈ (measures‘𝑆)) & ⊢ (𝜑 → 𝐴 ∈ 𝑆) & ⊢ (𝜑 → 𝐵 ∈ 𝑆) ⇒ ⊢ (𝜑 → (𝑀‘(𝐴 ∪ 𝐵)) ≤ ((𝑀‘𝐴) +𝑒 (𝑀‘𝐵))) | ||
| Theorem | measiuns 34218* | The measure of the union of a collection of sets, expressed as the sum of a disjoint set. This is used as a lemma for both measiun 34219 and meascnbl 34220. (Contributed by Thierry Arnoux, 22-Jan-2017.) (Proof shortened by Thierry Arnoux, 7-Feb-2017.) |
| ⊢ Ⅎ𝑛𝐵 & ⊢ (𝑛 = 𝑘 → 𝐴 = 𝐵) & ⊢ (𝜑 → (𝑁 = ℕ ∨ 𝑁 = (1..^𝐼))) & ⊢ (𝜑 → 𝑀 ∈ (measures‘𝑆)) & ⊢ ((𝜑 ∧ 𝑛 ∈ 𝑁) → 𝐴 ∈ 𝑆) ⇒ ⊢ (𝜑 → (𝑀‘∪ 𝑛 ∈ 𝑁 𝐴) = Σ*𝑛 ∈ 𝑁(𝑀‘(𝐴 ∖ ∪ 𝑘 ∈ (1..^𝑛)𝐵))) | ||
| Theorem | measiun 34219* | A measure is sub-additive. (Contributed by Thierry Arnoux, 30-Dec-2016.) (Proof shortened by Thierry Arnoux, 7-Feb-2017.) |
| ⊢ (𝜑 → 𝑀 ∈ (measures‘𝑆)) & ⊢ (𝜑 → 𝐴 ∈ 𝑆) & ⊢ ((𝜑 ∧ 𝑛 ∈ ℕ) → 𝐵 ∈ 𝑆) & ⊢ (𝜑 → 𝐴 ⊆ ∪ 𝑛 ∈ ℕ 𝐵) ⇒ ⊢ (𝜑 → (𝑀‘𝐴) ≤ Σ*𝑛 ∈ ℕ(𝑀‘𝐵)) | ||
| Theorem | meascnbl 34220* | A measure is continuous from below. Cf. volsup 25591. (Contributed by Thierry Arnoux, 18-Jan-2017.) (Revised by Thierry Arnoux, 11-Jul-2017.) |
| ⊢ 𝐽 = (TopOpen‘(ℝ*𝑠 ↾s (0[,]+∞))) & ⊢ (𝜑 → 𝑀 ∈ (measures‘𝑆)) & ⊢ (𝜑 → 𝐹:ℕ⟶𝑆) & ⊢ ((𝜑 ∧ 𝑛 ∈ ℕ) → (𝐹‘𝑛) ⊆ (𝐹‘(𝑛 + 1))) ⇒ ⊢ (𝜑 → (𝑀 ∘ 𝐹)(⇝𝑡‘𝐽)(𝑀‘∪ ran 𝐹)) | ||
| Theorem | measinblem 34221* | Lemma for measinb 34222. (Contributed by Thierry Arnoux, 2-Jun-2017.) |
| ⊢ ((((𝑀 ∈ (measures‘𝑆) ∧ 𝐴 ∈ 𝑆) ∧ 𝐵 ∈ 𝒫 𝑆) ∧ (𝐵 ≼ ω ∧ Disj 𝑥 ∈ 𝐵 𝑥)) → (𝑀‘(∪ 𝐵 ∩ 𝐴)) = Σ*𝑥 ∈ 𝐵(𝑀‘(𝑥 ∩ 𝐴))) | ||
| Theorem | measinb 34222* | Building a measure restricted to the intersection with a given set. (Contributed by Thierry Arnoux, 25-Dec-2016.) |
| ⊢ ((𝑀 ∈ (measures‘𝑆) ∧ 𝐴 ∈ 𝑆) → (𝑥 ∈ 𝑆 ↦ (𝑀‘(𝑥 ∩ 𝐴))) ∈ (measures‘𝑆)) | ||
| Theorem | measres 34223 | Building a measure restricted to a smaller sigma-algebra. (Contributed by Thierry Arnoux, 25-Dec-2016.) |
| ⊢ ((𝑀 ∈ (measures‘𝑆) ∧ 𝑇 ∈ ∪ ran sigAlgebra ∧ 𝑇 ⊆ 𝑆) → (𝑀 ↾ 𝑇) ∈ (measures‘𝑇)) | ||
| Theorem | measinb2 34224* | Building a measure restricted to the intersection with a given set. (Contributed by Thierry Arnoux, 25-Dec-2016.) |
| ⊢ ((𝑀 ∈ (measures‘𝑆) ∧ 𝐴 ∈ 𝑆) → (𝑥 ∈ (𝑆 ∩ 𝒫 𝐴) ↦ (𝑀‘(𝑥 ∩ 𝐴))) ∈ (measures‘(𝑆 ∩ 𝒫 𝐴))) | ||
| Theorem | measdivcst 34225 | Division of a measure by a positive constant is a measure. (Contributed by Thierry Arnoux, 25-Dec-2016.) (Revised by Thierry Arnoux, 30-Jan-2017.) |
| ⊢ ((𝑀 ∈ (measures‘𝑆) ∧ 𝐴 ∈ ℝ+) → (𝑀 ∘f/c /𝑒 𝐴) ∈ (measures‘𝑆)) | ||
| Theorem | measdivcstALTV 34226* | Alternate version of measdivcst 34225. (Contributed by Thierry Arnoux, 25-Dec-2016.) (New usage is discouraged.) |
| ⊢ ((𝑀 ∈ (measures‘𝑆) ∧ 𝐴 ∈ ℝ+) → (𝑥 ∈ 𝑆 ↦ ((𝑀‘𝑥) /𝑒 𝐴)) ∈ (measures‘𝑆)) | ||
| Theorem | cntmeas 34227 | The Counting measure is a measure on any sigma-algebra. (Contributed by Thierry Arnoux, 25-Dec-2016.) |
| ⊢ (𝑆 ∈ ∪ ran sigAlgebra → (♯ ↾ 𝑆) ∈ (measures‘𝑆)) | ||
| Theorem | pwcntmeas 34228 | The counting measure is a measure on any power set. (Contributed by Thierry Arnoux, 24-Jan-2017.) |
| ⊢ (𝑂 ∈ 𝑉 → (♯ ↾ 𝒫 𝑂) ∈ (measures‘𝒫 𝑂)) | ||
| Theorem | cntnevol 34229 | Counting and Lebesgue measures are different. (Contributed by Thierry Arnoux, 27-Jan-2017.) |
| ⊢ (♯ ↾ 𝒫 𝑂) ≠ vol | ||
| Theorem | voliune 34230 | The Lebesgue measure function is countably additive. This formulation on the extended reals, allows for +∞ for the measure of any set in the sum. Cf. ovoliun 25540 and voliun 25589. (Contributed by Thierry Arnoux, 16-Oct-2017.) |
| ⊢ ((∀𝑛 ∈ ℕ 𝐴 ∈ dom vol ∧ Disj 𝑛 ∈ ℕ 𝐴) → (vol‘∪ 𝑛 ∈ ℕ 𝐴) = Σ*𝑛 ∈ ℕ(vol‘𝐴)) | ||
| Theorem | volfiniune 34231* | The Lebesgue measure function is countably additive. This theorem is to volfiniun 25582 what voliune 34230 is to voliun 25589. (Contributed by Thierry Arnoux, 16-Oct-2017.) |
| ⊢ ((𝐴 ∈ Fin ∧ ∀𝑛 ∈ 𝐴 𝐵 ∈ dom vol ∧ Disj 𝑛 ∈ 𝐴 𝐵) → (vol‘∪ 𝑛 ∈ 𝐴 𝐵) = Σ*𝑛 ∈ 𝐴(vol‘𝐵)) | ||
| Theorem | volmeas 34232 | The Lebesgue measure is a measure. (Contributed by Thierry Arnoux, 16-Oct-2017.) |
| ⊢ vol ∈ (measures‘dom vol) | ||
| Syntax | cdde 34233 | Extend class notation to include the Dirac delta measure. |
| class δ | ||
| Definition | df-dde 34234 | Define the Dirac delta measure. (Contributed by Thierry Arnoux, 14-Sep-2018.) |
| ⊢ δ = (𝑎 ∈ 𝒫 ℝ ↦ if(0 ∈ 𝑎, 1, 0)) | ||
| Theorem | ddeval1 34235 | Value of the delta measure. (Contributed by Thierry Arnoux, 14-Sep-2018.) |
| ⊢ ((𝐴 ⊆ ℝ ∧ 0 ∈ 𝐴) → (δ‘𝐴) = 1) | ||
| Theorem | ddeval0 34236 | Value of the delta measure. (Contributed by Thierry Arnoux, 14-Sep-2018.) |
| ⊢ ((𝐴 ⊆ ℝ ∧ ¬ 0 ∈ 𝐴) → (δ‘𝐴) = 0) | ||
| Theorem | ddemeas 34237 | The Dirac delta measure is a measure. (Contributed by Thierry Arnoux, 14-Sep-2018.) |
| ⊢ δ ∈ (measures‘𝒫 ℝ) | ||
| Syntax | cae 34238 | Extend class notation to include the 'almost everywhere' relation. |
| class a.e. | ||
| Syntax | cfae 34239 | Extend class notation to include the 'almost everywhere' builder. |
| class ~ a.e. | ||
| Definition | df-ae 34240* | Define 'almost everywhere' with regard to a measure 𝑀. A property holds almost everywhere if the measure of the set where it does not hold has measure zero. (Contributed by Thierry Arnoux, 20-Oct-2017.) |
| ⊢ a.e. = {〈𝑎, 𝑚〉 ∣ (𝑚‘(∪ dom 𝑚 ∖ 𝑎)) = 0} | ||
| Theorem | relae 34241 | 'almost everywhere' is a relation. (Contributed by Thierry Arnoux, 20-Oct-2017.) |
| ⊢ Rel a.e. | ||
| Theorem | brae 34242 | 'almost everywhere' relation for a measure and a measurable set 𝐴. (Contributed by Thierry Arnoux, 20-Oct-2017.) |
| ⊢ ((𝑀 ∈ ∪ ran measures ∧ 𝐴 ∈ dom 𝑀) → (𝐴a.e.𝑀 ↔ (𝑀‘(∪ dom 𝑀 ∖ 𝐴)) = 0)) | ||
| Theorem | braew 34243* | 'almost everywhere' relation for a measure 𝑀 and a property 𝜑 (Contributed by Thierry Arnoux, 20-Oct-2017.) |
| ⊢ ∪ dom 𝑀 = 𝑂 ⇒ ⊢ (𝑀 ∈ ∪ ran measures → ({𝑥 ∈ 𝑂 ∣ 𝜑}a.e.𝑀 ↔ (𝑀‘{𝑥 ∈ 𝑂 ∣ ¬ 𝜑}) = 0)) | ||
| Theorem | truae 34244* | A truth holds almost everywhere. (Contributed by Thierry Arnoux, 20-Oct-2017.) |
| ⊢ ∪ dom 𝑀 = 𝑂 & ⊢ (𝜑 → 𝑀 ∈ ∪ ran measures) & ⊢ (𝜑 → 𝜓) ⇒ ⊢ (𝜑 → {𝑥 ∈ 𝑂 ∣ 𝜓}a.e.𝑀) | ||
| Theorem | aean 34245* | A conjunction holds almost everywhere if and only if both its terms do. (Contributed by Thierry Arnoux, 20-Oct-2017.) |
| ⊢ ∪ dom 𝑀 = 𝑂 ⇒ ⊢ ((𝑀 ∈ ∪ ran measures ∧ {𝑥 ∈ 𝑂 ∣ ¬ 𝜑} ∈ dom 𝑀 ∧ {𝑥 ∈ 𝑂 ∣ ¬ 𝜓} ∈ dom 𝑀) → ({𝑥 ∈ 𝑂 ∣ (𝜑 ∧ 𝜓)}a.e.𝑀 ↔ ({𝑥 ∈ 𝑂 ∣ 𝜑}a.e.𝑀 ∧ {𝑥 ∈ 𝑂 ∣ 𝜓}a.e.𝑀))) | ||
| Definition | df-fae 34246* | Define a builder for an 'almost everywhere' relation between functions, from relations between function values. In this definition, the range of 𝑓 and 𝑔 is enforced in order to ensure the resulting relation is a set. (Contributed by Thierry Arnoux, 22-Oct-2017.) |
| ⊢ ~ a.e. = (𝑟 ∈ V, 𝑚 ∈ ∪ ran measures ↦ {〈𝑓, 𝑔〉 ∣ ((𝑓 ∈ (dom 𝑟 ↑m ∪ dom 𝑚) ∧ 𝑔 ∈ (dom 𝑟 ↑m ∪ dom 𝑚)) ∧ {𝑥 ∈ ∪ dom 𝑚 ∣ (𝑓‘𝑥)𝑟(𝑔‘𝑥)}a.e.𝑚)}) | ||
| Theorem | faeval 34247* | Value of the 'almost everywhere' relation for a given relation and measure. (Contributed by Thierry Arnoux, 22-Oct-2017.) |
| ⊢ ((𝑅 ∈ V ∧ 𝑀 ∈ ∪ ran measures) → (𝑅~ a.e.𝑀) = {〈𝑓, 𝑔〉 ∣ ((𝑓 ∈ (dom 𝑅 ↑m ∪ dom 𝑀) ∧ 𝑔 ∈ (dom 𝑅 ↑m ∪ dom 𝑀)) ∧ {𝑥 ∈ ∪ dom 𝑀 ∣ (𝑓‘𝑥)𝑅(𝑔‘𝑥)}a.e.𝑀)}) | ||
| Theorem | relfae 34248 | The 'almost everywhere' builder for functions produces relations. (Contributed by Thierry Arnoux, 22-Oct-2017.) |
| ⊢ ((𝑅 ∈ V ∧ 𝑀 ∈ ∪ ran measures) → Rel (𝑅~ a.e.𝑀)) | ||
| Theorem | brfae 34249* | 'almost everywhere' relation for two functions 𝐹 and 𝐺 with regard to the measure 𝑀. (Contributed by Thierry Arnoux, 22-Oct-2017.) |
| ⊢ dom 𝑅 = 𝐷 & ⊢ (𝜑 → 𝑅 ∈ V) & ⊢ (𝜑 → 𝑀 ∈ ∪ ran measures) & ⊢ (𝜑 → 𝐹 ∈ (𝐷 ↑m ∪ dom 𝑀)) & ⊢ (𝜑 → 𝐺 ∈ (𝐷 ↑m ∪ dom 𝑀)) ⇒ ⊢ (𝜑 → (𝐹(𝑅~ a.e.𝑀)𝐺 ↔ {𝑥 ∈ ∪ dom 𝑀 ∣ (𝐹‘𝑥)𝑅(𝐺‘𝑥)}a.e.𝑀)) | ||
| Syntax | cmbfm 34250 | Extend class notation with the measurable functions builder. |
| class MblFnM | ||
| Definition | df-mbfm 34251* |
Define the measurable function builder, which generates the set of
measurable functions from a measurable space to another one. Here, the
measurable spaces are given using their sigma-algebras 𝑠 and
𝑡,
and the spaces themselves are recovered by ∪ 𝑠 and ∪ 𝑡.
Note the similarities between the definition of measurable functions in measure theory, and of continuous functions in topology. This is the definition for the generic measure theory. For the specific case of functions from ℝ to ℂ, see df-mbf 25654. (Contributed by Thierry Arnoux, 23-Jan-2017.) |
| ⊢ MblFnM = (𝑠 ∈ ∪ ran sigAlgebra, 𝑡 ∈ ∪ ran sigAlgebra ↦ {𝑓 ∈ (∪ 𝑡 ↑m ∪ 𝑠) ∣ ∀𝑥 ∈ 𝑡 (◡𝑓 “ 𝑥) ∈ 𝑠}) | ||
| Theorem | ismbfm 34252* | The predicate "𝐹 is a measurable function from the measurable space 𝑆 to the measurable space 𝑇". Cf. ismbf 25663. (Contributed by Thierry Arnoux, 23-Jan-2017.) |
| ⊢ (𝜑 → 𝑆 ∈ ∪ ran sigAlgebra) & ⊢ (𝜑 → 𝑇 ∈ ∪ ran sigAlgebra) ⇒ ⊢ (𝜑 → (𝐹 ∈ (𝑆MblFnM𝑇) ↔ (𝐹 ∈ (∪ 𝑇 ↑m ∪ 𝑆) ∧ ∀𝑥 ∈ 𝑇 (◡𝐹 “ 𝑥) ∈ 𝑆))) | ||
| Theorem | elunirnmbfm 34253* | The property of being a measurable function. (Contributed by Thierry Arnoux, 23-Jan-2017.) |
| ⊢ (𝐹 ∈ ∪ ran MblFnM ↔ ∃𝑠 ∈ ∪ ran sigAlgebra∃𝑡 ∈ ∪ ran sigAlgebra(𝐹 ∈ (∪ 𝑡 ↑m ∪ 𝑠) ∧ ∀𝑥 ∈ 𝑡 (◡𝐹 “ 𝑥) ∈ 𝑠)) | ||
| Theorem | mbfmfun 34254 | A measurable function is a function. (Contributed by Thierry Arnoux, 24-Jan-2017.) |
| ⊢ (𝜑 → 𝐹 ∈ ∪ ran MblFnM) ⇒ ⊢ (𝜑 → Fun 𝐹) | ||
| Theorem | mbfmf 34255 | A measurable function as a function with domain and codomain. (Contributed by Thierry Arnoux, 25-Jan-2017.) |
| ⊢ (𝜑 → 𝑆 ∈ ∪ ran sigAlgebra) & ⊢ (𝜑 → 𝑇 ∈ ∪ ran sigAlgebra) & ⊢ (𝜑 → 𝐹 ∈ (𝑆MblFnM𝑇)) ⇒ ⊢ (𝜑 → 𝐹:∪ 𝑆⟶∪ 𝑇) | ||
| Theorem | isanmbfmOLD 34256 | Obsolete version of isanmbfm 34258 as of 13-Jan-2025. (Contributed by Thierry Arnoux, 30-Jan-2017.) (Proof modification is discouraged.) (New usage is discouraged.) |
| ⊢ (𝜑 → 𝑆 ∈ ∪ ran sigAlgebra) & ⊢ (𝜑 → 𝑇 ∈ ∪ ran sigAlgebra) & ⊢ (𝜑 → 𝐹 ∈ (𝑆MblFnM𝑇)) ⇒ ⊢ (𝜑 → 𝐹 ∈ ∪ ran MblFnM) | ||
| Theorem | mbfmcnvima 34257 | The preimage by a measurable function is a measurable set. (Contributed by Thierry Arnoux, 23-Jan-2017.) |
| ⊢ (𝜑 → 𝑆 ∈ ∪ ran sigAlgebra) & ⊢ (𝜑 → 𝑇 ∈ ∪ ran sigAlgebra) & ⊢ (𝜑 → 𝐹 ∈ (𝑆MblFnM𝑇)) & ⊢ (𝜑 → 𝐴 ∈ 𝑇) ⇒ ⊢ (𝜑 → (◡𝐹 “ 𝐴) ∈ 𝑆) | ||
| Theorem | isanmbfm 34258 | The predicate to be a measurable function. (Contributed by Thierry Arnoux, 30-Jan-2017.) Remove hypotheses. (Revised by SN, 13-Jan-2025.) |
| ⊢ (𝜑 → 𝐹 ∈ (𝑆MblFnM𝑇)) ⇒ ⊢ (𝜑 → 𝐹 ∈ ∪ ran MblFnM) | ||
| Theorem | mbfmbfmOLD 34259 | A measurable function to a Borel Set is measurable. (Contributed by Thierry Arnoux, 24-Jan-2017.) (Proof modification is discouraged.) (New usage is discouraged.) |
| ⊢ (𝜑 → 𝑀 ∈ ∪ ran measures) & ⊢ (𝜑 → 𝐽 ∈ Top) & ⊢ (𝜑 → 𝐹 ∈ (dom 𝑀MblFnM(sigaGen‘𝐽))) ⇒ ⊢ (𝜑 → 𝐹 ∈ ∪ ran MblFnM) | ||
| Theorem | mbfmbfm 34260 | A measurable function to a Borel Set is measurable. (Contributed by Thierry Arnoux, 24-Jan-2017.) Remove hypotheses. (Revised by SN, 13-Jan-2025.) |
| ⊢ (𝜑 → 𝐹 ∈ (dom 𝑀MblFnM(sigaGen‘𝐽))) ⇒ ⊢ (𝜑 → 𝐹 ∈ ∪ ran MblFnM) | ||
| Theorem | mbfmcst 34261* | A constant function is measurable. Cf. mbfconst 25668. (Contributed by Thierry Arnoux, 26-Jan-2017.) |
| ⊢ (𝜑 → 𝑆 ∈ ∪ ran sigAlgebra) & ⊢ (𝜑 → 𝑇 ∈ ∪ ran sigAlgebra) & ⊢ (𝜑 → 𝐹 = (𝑥 ∈ ∪ 𝑆 ↦ 𝐴)) & ⊢ (𝜑 → 𝐴 ∈ ∪ 𝑇) ⇒ ⊢ (𝜑 → 𝐹 ∈ (𝑆MblFnM𝑇)) | ||
| Theorem | 1stmbfm 34262 | The first projection map is measurable with regard to the product sigma-algebra. (Contributed by Thierry Arnoux, 3-Jun-2017.) |
| ⊢ (𝜑 → 𝑆 ∈ ∪ ran sigAlgebra) & ⊢ (𝜑 → 𝑇 ∈ ∪ ran sigAlgebra) ⇒ ⊢ (𝜑 → (1st ↾ (∪ 𝑆 × ∪ 𝑇)) ∈ ((𝑆 ×s 𝑇)MblFnM𝑆)) | ||
| Theorem | 2ndmbfm 34263 | The second projection map is measurable with regard to the product sigma-algebra. (Contributed by Thierry Arnoux, 3-Jun-2017.) |
| ⊢ (𝜑 → 𝑆 ∈ ∪ ran sigAlgebra) & ⊢ (𝜑 → 𝑇 ∈ ∪ ran sigAlgebra) ⇒ ⊢ (𝜑 → (2nd ↾ (∪ 𝑆 × ∪ 𝑇)) ∈ ((𝑆 ×s 𝑇)MblFnM𝑇)) | ||
| Theorem | imambfm 34264* | If the sigma-algebra in the range of a given function is generated by a collection of basic sets 𝐾, then to check the measurability of that function, we need only consider inverse images of basic sets 𝑎. (Contributed by Thierry Arnoux, 4-Jun-2017.) |
| ⊢ (𝜑 → 𝐾 ∈ V) & ⊢ (𝜑 → 𝑆 ∈ ∪ ran sigAlgebra) & ⊢ (𝜑 → 𝑇 = (sigaGen‘𝐾)) ⇒ ⊢ (𝜑 → (𝐹 ∈ (𝑆MblFnM𝑇) ↔ (𝐹:∪ 𝑆⟶∪ 𝑇 ∧ ∀𝑎 ∈ 𝐾 (◡𝐹 “ 𝑎) ∈ 𝑆))) | ||
| Theorem | cnmbfm 34265 | A continuous function is measurable with respect to the Borel Algebra of its domain and range. (Contributed by Thierry Arnoux, 3-Jun-2017.) |
| ⊢ (𝜑 → 𝐹 ∈ (𝐽 Cn 𝐾)) & ⊢ (𝜑 → 𝑆 = (sigaGen‘𝐽)) & ⊢ (𝜑 → 𝑇 = (sigaGen‘𝐾)) ⇒ ⊢ (𝜑 → 𝐹 ∈ (𝑆MblFnM𝑇)) | ||
| Theorem | mbfmco 34266 | The composition of two measurable functions is measurable. See cnmpt11 23671. (Contributed by Thierry Arnoux, 4-Jun-2017.) |
| ⊢ (𝜑 → 𝑅 ∈ ∪ ran sigAlgebra) & ⊢ (𝜑 → 𝑆 ∈ ∪ ran sigAlgebra) & ⊢ (𝜑 → 𝑇 ∈ ∪ ran sigAlgebra) & ⊢ (𝜑 → 𝐹 ∈ (𝑅MblFnM𝑆)) & ⊢ (𝜑 → 𝐺 ∈ (𝑆MblFnM𝑇)) ⇒ ⊢ (𝜑 → (𝐺 ∘ 𝐹) ∈ (𝑅MblFnM𝑇)) | ||
| Theorem | mbfmco2 34267* | The pair building of two measurable functions is measurable. ( cf. cnmpt1t 23673). (Contributed by Thierry Arnoux, 6-Jun-2017.) |
| ⊢ (𝜑 → 𝑅 ∈ ∪ ran sigAlgebra) & ⊢ (𝜑 → 𝑆 ∈ ∪ ran sigAlgebra) & ⊢ (𝜑 → 𝑇 ∈ ∪ ran sigAlgebra) & ⊢ (𝜑 → 𝐹 ∈ (𝑅MblFnM𝑆)) & ⊢ (𝜑 → 𝐺 ∈ (𝑅MblFnM𝑇)) & ⊢ 𝐻 = (𝑥 ∈ ∪ 𝑅 ↦ 〈(𝐹‘𝑥), (𝐺‘𝑥)〉) ⇒ ⊢ (𝜑 → 𝐻 ∈ (𝑅MblFnM(𝑆 ×s 𝑇))) | ||
| Theorem | mbfmvolf 34268 | Measurable functions with respect to the Lebesgue measure are real-valued functions on the real numbers. (Contributed by Thierry Arnoux, 27-Mar-2017.) |
| ⊢ (𝐹 ∈ (dom volMblFnM𝔅ℝ) → 𝐹:ℝ⟶ℝ) | ||
| Theorem | elmbfmvol2 34269 | Measurable functions with respect to the Lebesgue measure. We only have the inclusion, since MblFn includes complex-valued functions. (Contributed by Thierry Arnoux, 26-Jan-2017.) |
| ⊢ (𝐹 ∈ (dom volMblFnM𝔅ℝ) → 𝐹 ∈ MblFn) | ||
| Theorem | mbfmcnt 34270 | All functions are measurable with respect to the counting measure. (Contributed by Thierry Arnoux, 24-Jan-2017.) |
| ⊢ (𝑂 ∈ 𝑉 → (𝒫 𝑂MblFnM𝔅ℝ) = (ℝ ↑m 𝑂)) | ||
| Theorem | br2base 34271* | The base set for the generator of the Borel sigma-algebra on (ℝ × ℝ) is indeed (ℝ × ℝ). (Contributed by Thierry Arnoux, 22-Sep-2017.) |
| ⊢ ∪ ran (𝑥 ∈ 𝔅ℝ, 𝑦 ∈ 𝔅ℝ ↦ (𝑥 × 𝑦)) = (ℝ × ℝ) | ||
| Theorem | dya2ub 34272 | An upper bound for a dyadic number. (Contributed by Thierry Arnoux, 19-Sep-2017.) |
| ⊢ (𝑅 ∈ ℝ+ → (1 / (2↑(⌊‘(1 − (2 logb 𝑅))))) < 𝑅) | ||
| Theorem | sxbrsigalem0 34273* | The closed half-spaces of (ℝ × ℝ) cover (ℝ × ℝ). (Contributed by Thierry Arnoux, 11-Oct-2017.) |
| ⊢ ∪ (ran (𝑒 ∈ ℝ ↦ ((𝑒[,)+∞) × ℝ)) ∪ ran (𝑓 ∈ ℝ ↦ (ℝ × (𝑓[,)+∞)))) = (ℝ × ℝ) | ||
| Theorem | sxbrsigalem3 34274* | The sigma-algebra generated by the closed half-spaces of (ℝ × ℝ) is a subset of the sigma-algebra generated by the closed sets of (ℝ × ℝ). (Contributed by Thierry Arnoux, 11-Oct-2017.) |
| ⊢ 𝐽 = (topGen‘ran (,)) ⇒ ⊢ (sigaGen‘(ran (𝑒 ∈ ℝ ↦ ((𝑒[,)+∞) × ℝ)) ∪ ran (𝑓 ∈ ℝ ↦ (ℝ × (𝑓[,)+∞))))) ⊆ (sigaGen‘(Clsd‘(𝐽 ×t 𝐽))) | ||
| Theorem | dya2iocival 34275* | The function 𝐼 returns closed-below open-above dyadic rational intervals covering the real line. This is the same construction as in dyadmbl 25635. (Contributed by Thierry Arnoux, 24-Sep-2017.) |
| ⊢ 𝐽 = (topGen‘ran (,)) & ⊢ 𝐼 = (𝑥 ∈ ℤ, 𝑛 ∈ ℤ ↦ ((𝑥 / (2↑𝑛))[,)((𝑥 + 1) / (2↑𝑛)))) ⇒ ⊢ ((𝑁 ∈ ℤ ∧ 𝑋 ∈ ℤ) → (𝑋𝐼𝑁) = ((𝑋 / (2↑𝑁))[,)((𝑋 + 1) / (2↑𝑁)))) | ||
| Theorem | dya2iocress 34276* | Dyadic intervals are subsets of ℝ. (Contributed by Thierry Arnoux, 18-Sep-2017.) |
| ⊢ 𝐽 = (topGen‘ran (,)) & ⊢ 𝐼 = (𝑥 ∈ ℤ, 𝑛 ∈ ℤ ↦ ((𝑥 / (2↑𝑛))[,)((𝑥 + 1) / (2↑𝑛)))) ⇒ ⊢ ((𝑁 ∈ ℤ ∧ 𝑋 ∈ ℤ) → (𝑋𝐼𝑁) ⊆ ℝ) | ||
| Theorem | dya2iocbrsiga 34277* | Dyadic intervals are Borel sets of ℝ. (Contributed by Thierry Arnoux, 22-Sep-2017.) |
| ⊢ 𝐽 = (topGen‘ran (,)) & ⊢ 𝐼 = (𝑥 ∈ ℤ, 𝑛 ∈ ℤ ↦ ((𝑥 / (2↑𝑛))[,)((𝑥 + 1) / (2↑𝑛)))) ⇒ ⊢ ((𝑁 ∈ ℤ ∧ 𝑋 ∈ ℤ) → (𝑋𝐼𝑁) ∈ 𝔅ℝ) | ||
| Theorem | dya2icobrsiga 34278* | Dyadic intervals are Borel sets of ℝ. (Contributed by Thierry Arnoux, 22-Sep-2017.) (Revised by Thierry Arnoux, 13-Oct-2017.) |
| ⊢ 𝐽 = (topGen‘ran (,)) & ⊢ 𝐼 = (𝑥 ∈ ℤ, 𝑛 ∈ ℤ ↦ ((𝑥 / (2↑𝑛))[,)((𝑥 + 1) / (2↑𝑛)))) ⇒ ⊢ ran 𝐼 ⊆ 𝔅ℝ | ||
| Theorem | dya2icoseg 34279* | For any point and any closed-below, open-above interval of ℝ centered on that point, there is a closed-below open-above dyadic rational interval which contains that point and is included in the original interval. (Contributed by Thierry Arnoux, 19-Sep-2017.) |
| ⊢ 𝐽 = (topGen‘ran (,)) & ⊢ 𝐼 = (𝑥 ∈ ℤ, 𝑛 ∈ ℤ ↦ ((𝑥 / (2↑𝑛))[,)((𝑥 + 1) / (2↑𝑛)))) & ⊢ 𝑁 = (⌊‘(1 − (2 logb 𝐷))) ⇒ ⊢ ((𝑋 ∈ ℝ ∧ 𝐷 ∈ ℝ+) → ∃𝑏 ∈ ran 𝐼(𝑋 ∈ 𝑏 ∧ 𝑏 ⊆ ((𝑋 − 𝐷)(,)(𝑋 + 𝐷)))) | ||
| Theorem | dya2icoseg2 34280* | For any point and any open interval of ℝ containing that point, there is a closed-below open-above dyadic rational interval which contains that point and is included in the original interval. (Contributed by Thierry Arnoux, 12-Oct-2017.) |
| ⊢ 𝐽 = (topGen‘ran (,)) & ⊢ 𝐼 = (𝑥 ∈ ℤ, 𝑛 ∈ ℤ ↦ ((𝑥 / (2↑𝑛))[,)((𝑥 + 1) / (2↑𝑛)))) ⇒ ⊢ ((𝑋 ∈ ℝ ∧ 𝐸 ∈ ran (,) ∧ 𝑋 ∈ 𝐸) → ∃𝑏 ∈ ran 𝐼(𝑋 ∈ 𝑏 ∧ 𝑏 ⊆ 𝐸)) | ||
| Theorem | dya2iocrfn 34281* | The function returning dyadic square covering for a given size has domain (ran 𝐼 × ran 𝐼). (Contributed by Thierry Arnoux, 19-Sep-2017.) |
| ⊢ 𝐽 = (topGen‘ran (,)) & ⊢ 𝐼 = (𝑥 ∈ ℤ, 𝑛 ∈ ℤ ↦ ((𝑥 / (2↑𝑛))[,)((𝑥 + 1) / (2↑𝑛)))) & ⊢ 𝑅 = (𝑢 ∈ ran 𝐼, 𝑣 ∈ ran 𝐼 ↦ (𝑢 × 𝑣)) ⇒ ⊢ 𝑅 Fn (ran 𝐼 × ran 𝐼) | ||
| Theorem | dya2iocct 34282* | The dyadic rectangle set is countable. (Contributed by Thierry Arnoux, 18-Sep-2017.) (Revised by Thierry Arnoux, 11-Oct-2017.) |
| ⊢ 𝐽 = (topGen‘ran (,)) & ⊢ 𝐼 = (𝑥 ∈ ℤ, 𝑛 ∈ ℤ ↦ ((𝑥 / (2↑𝑛))[,)((𝑥 + 1) / (2↑𝑛)))) & ⊢ 𝑅 = (𝑢 ∈ ran 𝐼, 𝑣 ∈ ran 𝐼 ↦ (𝑢 × 𝑣)) ⇒ ⊢ ran 𝑅 ≼ ω | ||
| Theorem | dya2iocnrect 34283* | For any point of an open rectangle in (ℝ × ℝ), there is a closed-below open-above dyadic rational square which contains that point and is included in the rectangle. (Contributed by Thierry Arnoux, 12-Oct-2017.) |
| ⊢ 𝐽 = (topGen‘ran (,)) & ⊢ 𝐼 = (𝑥 ∈ ℤ, 𝑛 ∈ ℤ ↦ ((𝑥 / (2↑𝑛))[,)((𝑥 + 1) / (2↑𝑛)))) & ⊢ 𝑅 = (𝑢 ∈ ran 𝐼, 𝑣 ∈ ran 𝐼 ↦ (𝑢 × 𝑣)) & ⊢ 𝐵 = ran (𝑒 ∈ ran (,), 𝑓 ∈ ran (,) ↦ (𝑒 × 𝑓)) ⇒ ⊢ ((𝑋 ∈ (ℝ × ℝ) ∧ 𝐴 ∈ 𝐵 ∧ 𝑋 ∈ 𝐴) → ∃𝑏 ∈ ran 𝑅(𝑋 ∈ 𝑏 ∧ 𝑏 ⊆ 𝐴)) | ||
| Theorem | dya2iocnei 34284* | For any point of an open set of the usual topology on (ℝ × ℝ) there is a closed-below open-above dyadic rational square which contains that point and is entirely in the open set. (Contributed by Thierry Arnoux, 21-Sep-2017.) |
| ⊢ 𝐽 = (topGen‘ran (,)) & ⊢ 𝐼 = (𝑥 ∈ ℤ, 𝑛 ∈ ℤ ↦ ((𝑥 / (2↑𝑛))[,)((𝑥 + 1) / (2↑𝑛)))) & ⊢ 𝑅 = (𝑢 ∈ ran 𝐼, 𝑣 ∈ ran 𝐼 ↦ (𝑢 × 𝑣)) ⇒ ⊢ ((𝐴 ∈ (𝐽 ×t 𝐽) ∧ 𝑋 ∈ 𝐴) → ∃𝑏 ∈ ran 𝑅(𝑋 ∈ 𝑏 ∧ 𝑏 ⊆ 𝐴)) | ||
| Theorem | dya2iocuni 34285* | Every open set of (ℝ × ℝ) is a union of closed-below open-above dyadic rational rectangular subsets of (ℝ × ℝ). This union must be a countable union by dya2iocct 34282. (Contributed by Thierry Arnoux, 18-Sep-2017.) |
| ⊢ 𝐽 = (topGen‘ran (,)) & ⊢ 𝐼 = (𝑥 ∈ ℤ, 𝑛 ∈ ℤ ↦ ((𝑥 / (2↑𝑛))[,)((𝑥 + 1) / (2↑𝑛)))) & ⊢ 𝑅 = (𝑢 ∈ ran 𝐼, 𝑣 ∈ ran 𝐼 ↦ (𝑢 × 𝑣)) ⇒ ⊢ (𝐴 ∈ (𝐽 ×t 𝐽) → ∃𝑐 ∈ 𝒫 ran 𝑅∪ 𝑐 = 𝐴) | ||
| Theorem | dya2iocucvr 34286* | The dyadic rectangular set collection covers (ℝ × ℝ). (Contributed by Thierry Arnoux, 18-Sep-2017.) |
| ⊢ 𝐽 = (topGen‘ran (,)) & ⊢ 𝐼 = (𝑥 ∈ ℤ, 𝑛 ∈ ℤ ↦ ((𝑥 / (2↑𝑛))[,)((𝑥 + 1) / (2↑𝑛)))) & ⊢ 𝑅 = (𝑢 ∈ ran 𝐼, 𝑣 ∈ ran 𝐼 ↦ (𝑢 × 𝑣)) ⇒ ⊢ ∪ ran 𝑅 = (ℝ × ℝ) | ||
| Theorem | sxbrsigalem1 34287* | The Borel algebra on (ℝ × ℝ) is a subset of the sigma-algebra generated by the dyadic closed-below, open-above rectangular subsets of (ℝ × ℝ). This is a step of the proof of Proposition 1.1.5 of [Cohn] p. 4. (Contributed by Thierry Arnoux, 17-Sep-2017.) |
| ⊢ 𝐽 = (topGen‘ran (,)) & ⊢ 𝐼 = (𝑥 ∈ ℤ, 𝑛 ∈ ℤ ↦ ((𝑥 / (2↑𝑛))[,)((𝑥 + 1) / (2↑𝑛)))) & ⊢ 𝑅 = (𝑢 ∈ ran 𝐼, 𝑣 ∈ ran 𝐼 ↦ (𝑢 × 𝑣)) ⇒ ⊢ (sigaGen‘(𝐽 ×t 𝐽)) ⊆ (sigaGen‘ran 𝑅) | ||
| Theorem | sxbrsigalem2 34288* | The sigma-algebra generated by the dyadic closed-below, open-above rectangular subsets of (ℝ × ℝ) is a subset of the sigma-algebra generated by the closed half-spaces of (ℝ × ℝ). The proof goes by noting the fact that the dyadic rectangles are intersections of a 'vertical band' and an 'horizontal band', which themselves are differences of closed half-spaces. (Contributed by Thierry Arnoux, 17-Sep-2017.) |
| ⊢ 𝐽 = (topGen‘ran (,)) & ⊢ 𝐼 = (𝑥 ∈ ℤ, 𝑛 ∈ ℤ ↦ ((𝑥 / (2↑𝑛))[,)((𝑥 + 1) / (2↑𝑛)))) & ⊢ 𝑅 = (𝑢 ∈ ran 𝐼, 𝑣 ∈ ran 𝐼 ↦ (𝑢 × 𝑣)) ⇒ ⊢ (sigaGen‘ran 𝑅) ⊆ (sigaGen‘(ran (𝑒 ∈ ℝ ↦ ((𝑒[,)+∞) × ℝ)) ∪ ran (𝑓 ∈ ℝ ↦ (ℝ × (𝑓[,)+∞))))) | ||
| Theorem | sxbrsigalem4 34289* | The Borel algebra on (ℝ × ℝ) is generated by the dyadic closed-below, open-above rectangular subsets of (ℝ × ℝ). Proposition 1.1.5 of [Cohn] p. 4 . Note that the interval used in this formalization are closed-below, open-above instead of open-below, closed-above in the proof as they are ultimately generated by the floor function. (Contributed by Thierry Arnoux, 21-Sep-2017.) |
| ⊢ 𝐽 = (topGen‘ran (,)) & ⊢ 𝐼 = (𝑥 ∈ ℤ, 𝑛 ∈ ℤ ↦ ((𝑥 / (2↑𝑛))[,)((𝑥 + 1) / (2↑𝑛)))) & ⊢ 𝑅 = (𝑢 ∈ ran 𝐼, 𝑣 ∈ ran 𝐼 ↦ (𝑢 × 𝑣)) ⇒ ⊢ (sigaGen‘(𝐽 ×t 𝐽)) = (sigaGen‘ran 𝑅) | ||
| Theorem | sxbrsigalem5 34290* | First direction for sxbrsiga 34292. (Contributed by Thierry Arnoux, 22-Sep-2017.) (Revised by Thierry Arnoux, 11-Oct-2017.) |
| ⊢ 𝐽 = (topGen‘ran (,)) & ⊢ 𝐼 = (𝑥 ∈ ℤ, 𝑛 ∈ ℤ ↦ ((𝑥 / (2↑𝑛))[,)((𝑥 + 1) / (2↑𝑛)))) & ⊢ 𝑅 = (𝑢 ∈ ran 𝐼, 𝑣 ∈ ran 𝐼 ↦ (𝑢 × 𝑣)) ⇒ ⊢ (sigaGen‘(𝐽 ×t 𝐽)) ⊆ (𝔅ℝ ×s 𝔅ℝ) | ||
| Theorem | sxbrsigalem6 34291 | First direction for sxbrsiga 34292, same as sxbrsigalem6, dealing with the antecedents. (Contributed by Thierry Arnoux, 10-Oct-2017.) |
| ⊢ 𝐽 = (topGen‘ran (,)) ⇒ ⊢ (sigaGen‘(𝐽 ×t 𝐽)) ⊆ (𝔅ℝ ×s 𝔅ℝ) | ||
| Theorem | sxbrsiga 34292 | The product sigma-algebra (𝔅ℝ ×s 𝔅ℝ) is the Borel algebra on (ℝ × ℝ) See example 5.1.1 of [Cohn] p. 143 . (Contributed by Thierry Arnoux, 10-Oct-2017.) |
| ⊢ 𝐽 = (topGen‘ran (,)) ⇒ ⊢ (𝔅ℝ ×s 𝔅ℝ) = (sigaGen‘(𝐽 ×t 𝐽)) | ||
In this section, we define a function toOMeas which constructs an outer measure, from a pre-measure 𝑅. An explicit generic definition of an outer measure is not given. It consists of the three following statements: - the outer measure of an empty set is zero (oms0 34299) - it is monotone (omsmon 34300) - it is countably sub-additive (omssubadd 34302) See Definition 1.11.1 of [Bogachev] p. 41. | ||
| Syntax | coms 34293 | Class declaration for the outer measure construction function. |
| class toOMeas | ||
| Definition | df-oms 34294* | Define a function constructing an outer measure. See omsval 34295 for its value. Definition 1.5 of [Bogachev] p. 16. (Contributed by Thierry Arnoux, 15-Sep-2019.) (Revised by AV, 4-Oct-2020.) |
| ⊢ toOMeas = (𝑟 ∈ V ↦ (𝑎 ∈ 𝒫 ∪ dom 𝑟 ↦ inf(ran (𝑥 ∈ {𝑧 ∈ 𝒫 dom 𝑟 ∣ (𝑎 ⊆ ∪ 𝑧 ∧ 𝑧 ≼ ω)} ↦ Σ*𝑦 ∈ 𝑥(𝑟‘𝑦)), (0[,]+∞), < ))) | ||
| Theorem | omsval 34295* | Value of the function mapping a content function to the corresponding outer measure. (Contributed by Thierry Arnoux, 15-Sep-2019.) (Revised by AV, 4-Oct-2020.) |
| ⊢ (𝑅 ∈ V → (toOMeas‘𝑅) = (𝑎 ∈ 𝒫 ∪ dom 𝑅 ↦ inf(ran (𝑥 ∈ {𝑧 ∈ 𝒫 dom 𝑅 ∣ (𝑎 ⊆ ∪ 𝑧 ∧ 𝑧 ≼ ω)} ↦ Σ*𝑦 ∈ 𝑥(𝑅‘𝑦)), (0[,]+∞), < ))) | ||
| Theorem | omsfval 34296* | Value of the outer measure evaluated for a given set 𝐴. (Contributed by Thierry Arnoux, 15-Sep-2019.) (Revised by AV, 4-Oct-2020.) |
| ⊢ ((𝑄 ∈ 𝑉 ∧ 𝑅:𝑄⟶(0[,]+∞) ∧ 𝐴 ⊆ ∪ 𝑄) → ((toOMeas‘𝑅)‘𝐴) = inf(ran (𝑥 ∈ {𝑧 ∈ 𝒫 dom 𝑅 ∣ (𝐴 ⊆ ∪ 𝑧 ∧ 𝑧 ≼ ω)} ↦ Σ*𝑦 ∈ 𝑥(𝑅‘𝑦)), (0[,]+∞), < )) | ||
| Theorem | omscl 34297* | A closure lemma for the constructed outer measure. (Contributed by Thierry Arnoux, 17-Sep-2019.) |
| ⊢ ((𝑄 ∈ 𝑉 ∧ 𝑅:𝑄⟶(0[,]+∞) ∧ 𝐴 ∈ 𝒫 ∪ dom 𝑅) → ran (𝑥 ∈ {𝑧 ∈ 𝒫 dom 𝑅 ∣ (𝐴 ⊆ ∪ 𝑧 ∧ 𝑧 ≼ ω)} ↦ Σ*𝑦 ∈ 𝑥(𝑅‘𝑦)) ⊆ (0[,]+∞)) | ||
| Theorem | omsf 34298 | A constructed outer measure is a function. (Contributed by Thierry Arnoux, 17-Sep-2019.) (Revised by AV, 4-Oct-2020.) |
| ⊢ ((𝑄 ∈ 𝑉 ∧ 𝑅:𝑄⟶(0[,]+∞)) → (toOMeas‘𝑅):𝒫 ∪ dom 𝑅⟶(0[,]+∞)) | ||
| Theorem | oms0 34299 | A constructed outer measure evaluates to zero for the empty set. (Contributed by Thierry Arnoux, 15-Sep-2019.) (Revised by AV, 4-Oct-2020.) |
| ⊢ 𝑀 = (toOMeas‘𝑅) & ⊢ (𝜑 → 𝑄 ∈ 𝑉) & ⊢ (𝜑 → 𝑅:𝑄⟶(0[,]+∞)) & ⊢ (𝜑 → ∅ ∈ dom 𝑅) & ⊢ (𝜑 → (𝑅‘∅) = 0) ⇒ ⊢ (𝜑 → (𝑀‘∅) = 0) | ||
| Theorem | omsmon 34300 | A constructed outer measure is monotone. Note in Example 1.5.2 of [Bogachev] p. 17. (Contributed by Thierry Arnoux, 15-Sep-2019.) (Revised by AV, 4-Oct-2020.) |
| ⊢ 𝑀 = (toOMeas‘𝑅) & ⊢ (𝜑 → 𝑄 ∈ 𝑉) & ⊢ (𝜑 → 𝑅:𝑄⟶(0[,]+∞)) & ⊢ (𝜑 → 𝐴 ⊆ 𝐵) & ⊢ (𝜑 → 𝐵 ⊆ ∪ 𝑄) ⇒ ⊢ (𝜑 → (𝑀‘𝐴) ≤ (𝑀‘𝐵)) | ||
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