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Measurable Function

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Definition
MeasureTheory

Let (X,FX),(Y,FY)(X,\mathcal{F}_{X}),(Y,\mathcal{F}_{Y}) be measurable spaces. Let g:(X,FX)β†’(Y,FY)g:(X,\mathcal{F}_{X})\to(Y,\mathcal{F}_{Y}) be a mapping. gg is called a measurable function if βˆ€A∈FY:gβˆ’1(A)∈FX\forall A\in\mathcal{F}_{Y}:g^{-1}(A)\in\mathcal{F}_{X}i.e.Β the pre-images of all sets in the output Οƒ-algebra are in the Οƒ-algebra of the input space.


In the context of our analysis class we can examine this definition from the POV of topological spaces

Let (X,M)(X,\mathcal{M}) be a measurable space and (Y,T)(Y,\mathscr{T}) be a topological space. We say f:Xβ†’Yf:X\to Y is measurable if βˆ€B∈T:fβˆ’1(B)∈M\forall B\in\mathscr{T}:f^{-1}(B)\in\mathcal{M}

Linked from

A Summary of MATH 891

Borel function

Οƒ-algebra containing all Borel subsets

Limit of Measurable Functions is Measurable

Measurability Criterion for Topological Codomain

Supremum & Infimum Preserve Measurability

HΓΆlder's Inequality

Jensen's Inequality

Minkowski's Inequality

Law

Lebesgue-Stieltjes Integral

Convolution

Lebesgue Integral

Change of Variable Formula

Beppo Levi Theorem

Dominated Convergence Theorem

Fatou's Lemma

Monotone Convergence Theorem

Lebesgue Integral is a Measure

Essential bound

Integrable

Integrals of Functions that are Zero a.e.

Simple Function

Closure of Measurability

Composition of Measurable Functions

Criterion for Measurability

Function of real measurable functions is measurable

Measurability of Continuous Functions

Pushforward Measure

Fubini-Tonelli

Slices of product measurable function are in measurable in resultant Οƒ-algebras

Total Variation

Admissible Policy

Measurable Selection Conditions

Controlled Markov Chain

Blackwell's Irrelevant Information Theorem

Discounted Cost

Belief MDP

Kalman Filter

Static Quadratic Team

Witsenhausen's Intrinsic Model

Norm-like Function

Conditional Expectation

Random Variable

(Ξ›) Set of Predictable Locally Integrable Processes

Semimartingale

Bichteler-Dellacherie Theorem

Independence of Bounded RV

Left Continuous Adapted = Predictable

Replicating Portfolio

Disintegration

Feller Property

Local Martingale

Doob's Upcrossing Inequality

Martingale Convergence Theorem

Stochastic Kernel

Random Time

Ionescu Tulcea Theorem