P. 343 of Theorem List - Metamath Proof Explorer

Theorem List for Metamath Proof Explorer - 34201-34300   *Has distinct variable group(s)

Type	Label	Description
Statement
Theorem	measinb 34201*	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 34202	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 34203*	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 34204	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 34205*	Alternate version of measdivcst 34204. (Contributed by Thierry Arnoux, 25-Dec-2016.) (New usage is discouraged.)
⊢ ((𝑀 ∈ (measures‘𝑆) ∧ 𝐴 ∈ ℝ+) → (𝑥 ∈ 𝑆 ↦ ((𝑀‘𝑥) /𝑒 𝐴)) ∈ (measures‘𝑆))
21.3.18.7  The counting measure
Theorem	cntmeas 34206	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 34207	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 34208	Counting and Lebesgue measures are different. (Contributed by Thierry Arnoux, 27-Jan-2017.)
⊢ (♯ ↾ 𝒫 𝑂) ≠ vol
21.3.18.8  The Lebesgue measure - misc additions
Theorem	voliune 34209	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 25553 and voliun 25602. (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 34210*	The Lebesgue measure function is countably additive. This theorem is to volfiniun 25595 what voliune 34209 is to voliun 25602. (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 34211	The Lebesgue measure is a measure. (Contributed by Thierry Arnoux, 16-Oct-2017.)
⊢ vol ∈ (measures‘dom vol)
21.3.18.9  The Dirac delta measure
Syntax	cdde 34212	Extend class notation to include the Dirac delta measure.
class δ
Definition	df-dde 34213	Define the Dirac delta measure. (Contributed by Thierry Arnoux, 14-Sep-2018.)
⊢ δ = (𝑎 ∈ 𝒫 ℝ ↦ if(0 ∈ 𝑎, 1, 0))
Theorem	ddeval1 34214	Value of the delta measure. (Contributed by Thierry Arnoux, 14-Sep-2018.)
⊢ ((𝐴 ⊆ ℝ ∧ 0 ∈ 𝐴) → (δ‘𝐴) = 1)
Theorem	ddeval0 34215	Value of the delta measure. (Contributed by Thierry Arnoux, 14-Sep-2018.)
⊢ ((𝐴 ⊆ ℝ ∧ ¬ 0 ∈ 𝐴) → (δ‘𝐴) = 0)
Theorem	ddemeas 34216	The Dirac delta measure is a measure. (Contributed by Thierry Arnoux, 14-Sep-2018.)
⊢ δ ∈ (measures‘𝒫 ℝ)
21.3.18.10  The 'almost everywhere' relation
Syntax	cae 34217	Extend class notation to include the 'almost everywhere' relation.
class a.e.
Syntax	cfae 34218	Extend class notation to include the 'almost everywhere' builder.
class ~ a.e.
Definition	df-ae 34219*	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 34220	'almost everywhere' is a relation. (Contributed by Thierry Arnoux, 20-Oct-2017.)
⊢ Rel a.e.
Theorem	brae 34221	'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 34222*	'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 34223*	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 34224*	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 34225*	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 34226*	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 34227	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 34228*	'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))
21.3.18.11  Measurable functions
Syntax	cmbfm 34229	Extend class notation with the measurable functions builder.
class MblFnM
Definition	df-mbfm 34230*	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 25667. (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 34231*	The predicate "𝐹 is a measurable function from the measurable space 𝑆 to the measurable space 𝑇". Cf. ismbf 25676. (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 34232*	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 34233	A measurable function is a function. (Contributed by Thierry Arnoux, 24-Jan-2017.)
⊢ (𝜑 → 𝐹 ∈ ∪ ran MblFnM)    ⇒   ⊢ (𝜑 → Fun 𝐹)
Theorem	mbfmf 34234	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 34235	Obsolete version of isanmbfm 34237 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 34236	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 34237	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 34238	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 34239	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 34240*	A constant function is measurable. Cf. mbfconst 25681. (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 34241	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 34242	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 34243*	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 34244	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 34245	The composition of two measurable functions is measurable. See cnmpt11 23686. (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 34246*	The pair building of two measurable functions is measurable. ( cf. cnmpt1t 23688). (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 34247	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 34248	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 34249	All functions are measurable with respect to the counting measure. (Contributed by Thierry Arnoux, 24-Jan-2017.)
⊢ (𝑂 ∈ 𝑉 → (𝒫 𝑂MblFnM𝔅ℝ) = (ℝ ↑m 𝑂))
21.3.18.12  Borel Algebra on ` ( RR X. RR ) `
Theorem	br2base 34250*	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 34251	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 34252*	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 34253*	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 34254*	The function 𝐼 returns closed-below open-above dyadic rational intervals covering the real line. This is the same construction as in dyadmbl 25648. (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 34255*	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 34256*	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 34257*	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 34258*	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 34259*	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 34260*	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 34261*	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 34262*	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 34263*	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 34264*	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 34261. (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 34265*	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 34266*	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 34267*	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 34268*	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 34269*	First direction for sxbrsiga 34271. (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 34270	First direction for sxbrsiga 34271, 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 34271	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))
21.3.18.13  Caratheodory's extension theorem 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 34278) - it is monotone (omsmon 34279) - it is countably sub-additive (omssubadd 34281) See Definition 1.11.1 of [Bogachev] p. 41.
Syntax	coms 34272	Class declaration for the outer measure construction function.
class toOMeas
Definition	df-oms 34273*	Define a function constructing an outer measure. See omsval 34274 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 34274*	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 34275*	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 34276*	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 34277	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 34278	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 34279	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))
Theorem	omssubaddlem 34280*	For any small margin 𝐸, we can find a covering approaching the outer measure of a set 𝐴 by that margin. (Contributed by Thierry Arnoux, 18-Sep-2019.) (Revised by AV, 4-Oct-2020.)
⊢ 𝑀 = (toOMeas‘𝑅)    &   ⊢ (𝜑 → 𝑄 ∈ 𝑉)    &   ⊢ (𝜑 → 𝑅:𝑄⟶(0[,]+∞))    &   ⊢ (𝜑 → 𝐴 ⊆ ∪ 𝑄)    &   ⊢ (𝜑 → (𝑀‘𝐴) ∈ ℝ)    &   ⊢ (𝜑 → 𝐸 ∈ ℝ+)    ⇒   ⊢ (𝜑 → ∃𝑥 ∈ {𝑧 ∈ 𝒫 dom 𝑅 ∣ (𝐴 ⊆ ∪ 𝑧 ∧ 𝑧 ≼ ω)}Σ*𝑤 ∈ 𝑥(𝑅‘𝑤) < ((𝑀‘𝐴) + 𝐸))
Theorem	omssubadd 34281*	A constructed outer measure is countably sub-additive. Lemma 1.5.4 of [Bogachev] p. 17. (Contributed by Thierry Arnoux, 21-Sep-2019.) (Revised by AV, 4-Oct-2020.)
⊢ 𝑀 = (toOMeas‘𝑅)    &   ⊢ (𝜑 → 𝑄 ∈ 𝑉)    &   ⊢ (𝜑 → 𝑅:𝑄⟶(0[,]+∞))    &   ⊢ ((𝜑 ∧ 𝑦 ∈ 𝑋) → 𝐴 ⊆ ∪ 𝑄)    &   ⊢ (𝜑 → 𝑋 ≼ ω)    ⇒   ⊢ (𝜑 → (𝑀‘∪ 𝑦 ∈ 𝑋 𝐴) ≤ Σ*𝑦 ∈ 𝑋(𝑀‘𝐴))
Syntax	ccarsg 34282	Class declaration for the Caratheodory sigma-Algebra construction.
class toCaraSiga
Definition	df-carsg 34283*	Define a function constructing Caratheodory measurable sets for a given outer measure. See carsgval 34284 for its value. Definition 1.11.2 of [Bogachev] p. 41. (Contributed by Thierry Arnoux, 17-May-2020.)
⊢ toCaraSiga = (𝑚 ∈ V ↦ {𝑎 ∈ 𝒫 ∪ dom 𝑚 ∣ ∀𝑒 ∈ 𝒫 ∪ dom 𝑚((𝑚‘(𝑒 ∩ 𝑎)) +𝑒 (𝑚‘(𝑒 ∖ 𝑎))) = (𝑚‘𝑒)})
Theorem	carsgval 34284*	Value of the Caratheodory sigma-Algebra construction function. (Contributed by Thierry Arnoux, 17-May-2020.)
⊢ (𝜑 → 𝑂 ∈ 𝑉)    &   ⊢ (𝜑 → 𝑀:𝒫 𝑂⟶(0[,]+∞))    ⇒   ⊢ (𝜑 → (toCaraSiga‘𝑀) = {𝑎 ∈ 𝒫 𝑂 ∣ ∀𝑒 ∈ 𝒫 𝑂((𝑀‘(𝑒 ∩ 𝑎)) +𝑒 (𝑀‘(𝑒 ∖ 𝑎))) = (𝑀‘𝑒)})
Theorem	carsgcl 34285	Closure of the Caratheodory measurable sets. (Contributed by Thierry Arnoux, 17-May-2020.)
⊢ (𝜑 → 𝑂 ∈ 𝑉)    &   ⊢ (𝜑 → 𝑀:𝒫 𝑂⟶(0[,]+∞))    ⇒   ⊢ (𝜑 → (toCaraSiga‘𝑀) ⊆ 𝒫 𝑂)
Theorem	elcarsg 34286*	Property of being a Caratheodory measurable set. (Contributed by Thierry Arnoux, 17-May-2020.)
⊢ (𝜑 → 𝑂 ∈ 𝑉)    &   ⊢ (𝜑 → 𝑀:𝒫 𝑂⟶(0[,]+∞))    ⇒   ⊢ (𝜑 → (𝐴 ∈ (toCaraSiga‘𝑀) ↔ (𝐴 ⊆ 𝑂 ∧ ∀𝑒 ∈ 𝒫 𝑂((𝑀‘(𝑒 ∩ 𝐴)) +𝑒 (𝑀‘(𝑒 ∖ 𝐴))) = (𝑀‘𝑒))))
Theorem	baselcarsg 34287	The universe set, 𝑂, is Caratheodory measurable. (Contributed by Thierry Arnoux, 17-May-2020.)
⊢ (𝜑 → 𝑂 ∈ 𝑉)    &   ⊢ (𝜑 → 𝑀:𝒫 𝑂⟶(0[,]+∞))    &   ⊢ (𝜑 → (𝑀‘∅) = 0)    ⇒   ⊢ (𝜑 → 𝑂 ∈ (toCaraSiga‘𝑀))
Theorem	0elcarsg 34288	The empty set is Caratheodory measurable. (Contributed by Thierry Arnoux, 30-May-2020.)
⊢ (𝜑 → 𝑂 ∈ 𝑉)    &   ⊢ (𝜑 → 𝑀:𝒫 𝑂⟶(0[,]+∞))    &   ⊢ (𝜑 → (𝑀‘∅) = 0)    ⇒   ⊢ (𝜑 → ∅ ∈ (toCaraSiga‘𝑀))
Theorem	carsguni 34289	The union of all Caratheodory measurable sets is the universe. (Contributed by Thierry Arnoux, 22-May-2020.)
⊢ (𝜑 → 𝑂 ∈ 𝑉)    &   ⊢ (𝜑 → 𝑀:𝒫 𝑂⟶(0[,]+∞))    &   ⊢ (𝜑 → (𝑀‘∅) = 0)    ⇒   ⊢ (𝜑 → ∪ (toCaraSiga‘𝑀) = 𝑂)
Theorem	elcarsgss 34290	Caratheodory measurable sets are subsets of the universe. (Contributed by Thierry Arnoux, 21-May-2020.)
⊢ (𝜑 → 𝑂 ∈ 𝑉)    &   ⊢ (𝜑 → 𝑀:𝒫 𝑂⟶(0[,]+∞))    &   ⊢ (𝜑 → 𝐴 ∈ (toCaraSiga‘𝑀))    ⇒   ⊢ (𝜑 → 𝐴 ⊆ 𝑂)
Theorem	difelcarsg 34291	The Caratheodory measurable sets are closed under complement. (Contributed by Thierry Arnoux, 17-May-2020.)
⊢ (𝜑 → 𝑂 ∈ 𝑉)    &   ⊢ (𝜑 → 𝑀:𝒫 𝑂⟶(0[,]+∞))    &   ⊢ (𝜑 → 𝐴 ∈ (toCaraSiga‘𝑀))    ⇒   ⊢ (𝜑 → (𝑂 ∖ 𝐴) ∈ (toCaraSiga‘𝑀))
Theorem	inelcarsg 34292*	The Caratheodory measurable sets are closed under intersection. (Contributed by Thierry Arnoux, 18-May-2020.)
⊢ (𝜑 → 𝑂 ∈ 𝑉)    &   ⊢ (𝜑 → 𝑀:𝒫 𝑂⟶(0[,]+∞))    &   ⊢ (𝜑 → 𝐴 ∈ (toCaraSiga‘𝑀))    &   ⊢ ((𝜑 ∧ 𝑎 ∈ 𝒫 𝑂 ∧ 𝑏 ∈ 𝒫 𝑂) → (𝑀‘(𝑎 ∪ 𝑏)) ≤ ((𝑀‘𝑎) +𝑒 (𝑀‘𝑏)))    &   ⊢ (𝜑 → 𝐵 ∈ (toCaraSiga‘𝑀))    ⇒   ⊢ (𝜑 → (𝐴 ∩ 𝐵) ∈ (toCaraSiga‘𝑀))
Theorem	unelcarsg 34293*	The Caratheodory-measurable sets are closed under pairwise unions. (Contributed by Thierry Arnoux, 21-May-2020.)
⊢ (𝜑 → 𝑂 ∈ 𝑉)    &   ⊢ (𝜑 → 𝑀:𝒫 𝑂⟶(0[,]+∞))    &   ⊢ (𝜑 → 𝐴 ∈ (toCaraSiga‘𝑀))    &   ⊢ ((𝜑 ∧ 𝑎 ∈ 𝒫 𝑂 ∧ 𝑏 ∈ 𝒫 𝑂) → (𝑀‘(𝑎 ∪ 𝑏)) ≤ ((𝑀‘𝑎) +𝑒 (𝑀‘𝑏)))    &   ⊢ (𝜑 → 𝐵 ∈ (toCaraSiga‘𝑀))    ⇒   ⊢ (𝜑 → (𝐴 ∪ 𝐵) ∈ (toCaraSiga‘𝑀))
Theorem	difelcarsg2 34294*	The Caratheodory-measurable sets are closed under class difference. (Contributed by Thierry Arnoux, 30-May-2020.)
⊢ (𝜑 → 𝑂 ∈ 𝑉)    &   ⊢ (𝜑 → 𝑀:𝒫 𝑂⟶(0[,]+∞))    &   ⊢ (𝜑 → 𝐴 ∈ (toCaraSiga‘𝑀))    &   ⊢ ((𝜑 ∧ 𝑎 ∈ 𝒫 𝑂 ∧ 𝑏 ∈ 𝒫 𝑂) → (𝑀‘(𝑎 ∪ 𝑏)) ≤ ((𝑀‘𝑎) +𝑒 (𝑀‘𝑏)))    &   ⊢ (𝜑 → 𝐵 ∈ (toCaraSiga‘𝑀))    ⇒   ⊢ (𝜑 → (𝐴 ∖ 𝐵) ∈ (toCaraSiga‘𝑀))
Theorem	carsgmon 34295*	Utility lemma: Apply monotony. (Contributed by Thierry Arnoux, 29-May-2020.)
⊢ (𝜑 → 𝑂 ∈ 𝑉)    &   ⊢ (𝜑 → 𝑀:𝒫 𝑂⟶(0[,]+∞))    &   ⊢ (𝜑 → 𝐴 ⊆ 𝐵)    &   ⊢ (𝜑 → 𝐵 ∈ 𝒫 𝑂)    &   ⊢ ((𝜑 ∧ 𝑥 ⊆ 𝑦 ∧ 𝑦 ∈ 𝒫 𝑂) → (𝑀‘𝑥) ≤ (𝑀‘𝑦))    ⇒   ⊢ (𝜑 → (𝑀‘𝐴) ≤ (𝑀‘𝐵))
Theorem	carsgsigalem 34296*	Lemma for the following theorems. (Contributed by Thierry Arnoux, 23-May-2020.)
⊢ (𝜑 → 𝑂 ∈ 𝑉)    &   ⊢ (𝜑 → 𝑀:𝒫 𝑂⟶(0[,]+∞))    &   ⊢ (𝜑 → (𝑀‘∅) = 0)    &   ⊢ ((𝜑 ∧ 𝑥 ≼ ω ∧ 𝑥 ⊆ 𝒫 𝑂) → (𝑀‘∪ 𝑥) ≤ Σ*𝑦 ∈ 𝑥(𝑀‘𝑦))    ⇒   ⊢ ((𝜑 ∧ 𝑒 ∈ 𝒫 𝑂 ∧ 𝑓 ∈ 𝒫 𝑂) → (𝑀‘(𝑒 ∪ 𝑓)) ≤ ((𝑀‘𝑒) +𝑒 (𝑀‘𝑓)))
Theorem	fiunelcarsg 34297*	The Caratheodory measurable sets are closed under finite union. (Contributed by Thierry Arnoux, 23-May-2020.)
⊢ (𝜑 → 𝑂 ∈ 𝑉)    &   ⊢ (𝜑 → 𝑀:𝒫 𝑂⟶(0[,]+∞))    &   ⊢ (𝜑 → (𝑀‘∅) = 0)    &   ⊢ ((𝜑 ∧ 𝑥 ≼ ω ∧ 𝑥 ⊆ 𝒫 𝑂) → (𝑀‘∪ 𝑥) ≤ Σ*𝑦 ∈ 𝑥(𝑀‘𝑦))    &   ⊢ (𝜑 → 𝐴 ∈ Fin)    &   ⊢ (𝜑 → 𝐴 ⊆ (toCaraSiga‘𝑀))    ⇒   ⊢ (𝜑 → ∪ 𝐴 ∈ (toCaraSiga‘𝑀))
Theorem	carsgclctunlem1 34298*	Lemma for carsgclctun 34302. (Contributed by Thierry Arnoux, 23-May-2020.)
⊢ (𝜑 → 𝑂 ∈ 𝑉)    &   ⊢ (𝜑 → 𝑀:𝒫 𝑂⟶(0[,]+∞))    &   ⊢ (𝜑 → (𝑀‘∅) = 0)    &   ⊢ ((𝜑 ∧ 𝑥 ≼ ω ∧ 𝑥 ⊆ 𝒫 𝑂) → (𝑀‘∪ 𝑥) ≤ Σ*𝑦 ∈ 𝑥(𝑀‘𝑦))    &   ⊢ (𝜑 → 𝐴 ∈ Fin)    &   ⊢ (𝜑 → 𝐴 ⊆ (toCaraSiga‘𝑀))    &   ⊢ (𝜑 → Disj 𝑦 ∈ 𝐴 𝑦)    &   ⊢ (𝜑 → 𝐸 ∈ 𝒫 𝑂)    ⇒   ⊢ (𝜑 → (𝑀‘(𝐸 ∩ ∪ 𝐴)) = Σ*𝑦 ∈ 𝐴(𝑀‘(𝐸 ∩ 𝑦)))
Theorem	carsggect 34299*	The outer measure is countably superadditive on Caratheodory measurable sets. (Contributed by Thierry Arnoux, 31-May-2020.)
⊢ (𝜑 → 𝑂 ∈ 𝑉)    &   ⊢ (𝜑 → 𝑀:𝒫 𝑂⟶(0[,]+∞))    &   ⊢ (𝜑 → (𝑀‘∅) = 0)    &   ⊢ ((𝜑 ∧ 𝑥 ≼ ω ∧ 𝑥 ⊆ 𝒫 𝑂) → (𝑀‘∪ 𝑥) ≤ Σ*𝑦 ∈ 𝑥(𝑀‘𝑦))    &   ⊢ (𝜑 → ¬ ∅ ∈ 𝐴)    &   ⊢ (𝜑 → 𝐴 ≼ ω)    &   ⊢ (𝜑 → 𝐴 ⊆ (toCaraSiga‘𝑀))    &   ⊢ (𝜑 → Disj 𝑦 ∈ 𝐴 𝑦)    &   ⊢ ((𝜑 ∧ 𝑥 ⊆ 𝑦 ∧ 𝑦 ∈ 𝒫 𝑂) → (𝑀‘𝑥) ≤ (𝑀‘𝑦))    ⇒   ⊢ (𝜑 → Σ*𝑧 ∈ 𝐴(𝑀‘𝑧) ≤ (𝑀‘∪ 𝐴))
Theorem	carsgclctunlem2 34300*	Lemma for carsgclctun 34302. (Contributed by Thierry Arnoux, 25-May-2020.)
⊢ (𝜑 → 𝑂 ∈ 𝑉)    &   ⊢ (𝜑 → 𝑀:𝒫 𝑂⟶(0[,]+∞))    &   ⊢ (𝜑 → (𝑀‘∅) = 0)    &   ⊢ ((𝜑 ∧ 𝑥 ≼ ω ∧ 𝑥 ⊆ 𝒫 𝑂) → (𝑀‘∪ 𝑥) ≤ Σ*𝑦 ∈ 𝑥(𝑀‘𝑦))    &   ⊢ ((𝜑 ∧ 𝑥 ⊆ 𝑦 ∧ 𝑦 ∈ 𝒫 𝑂) → (𝑀‘𝑥) ≤ (𝑀‘𝑦))    &   ⊢ (𝜑 → Disj 𝑘 ∈ ℕ 𝐴)    &   ⊢ ((𝜑 ∧ 𝑘 ∈ ℕ) → 𝐴 ∈ (toCaraSiga‘𝑀))    &   ⊢ (𝜑 → 𝐸 ∈ 𝒫 𝑂)    &   ⊢ (𝜑 → (𝑀‘𝐸) ≠ +∞)    ⇒   ⊢ (𝜑 → ((𝑀‘(𝐸 ∩ ∪ 𝑘 ∈ ℕ 𝐴)) +𝑒 (𝑀‘(𝐸 ∖ ∪ 𝑘 ∈ ℕ 𝐴))) ≤ (𝑀‘𝐸))