Questions tagged [signed-measures]
A signed measure is a countably additive set function on a sigma-algebra and taking values in the extended reals, but not permitted to assign negative infinity to a set.
141 questions
1 vote
1 answer
86 views
Downwards monotone convergence is unavailable for signed measures
For unsigned measure $\mu$ on a measurable space $(X, \mathcal B)$, we have: (Downwards monotone convergence) If ${E_1 \supset E_2 \supset \ldots}$ are ${{\mathcal B}}$-measurable, and ${\mu(E_n)<\...
0 votes
0 answers
36 views
Approximating class for signed measure
Given a finite signed measure $\mu$ on a $\sigma$-algebra $\mathcal{A}$, we say that $\mathcal{K}$ is an approximating class for $\mu$ on $\mathcal{A}$ if, for every $A\in\mathcal{A},\varepsilon>0$ ...
0 votes
1 answer
64 views
Total variation is a measure; Le Gall
I'm reading Measure Theory, Probability and Stochastic Processes by Le Gall. I'm stuck on a claim in a theorem (Theorem 6.2) on the total variation of a signed measure. Consider the definition of ...
1 vote
0 answers
31 views
About max and min of bounded signed measure
If $\mu$ is a bounded signed measure on a measurable space $(\mathcal{F}, \Omega)$, then there exist $A_1, A_2$ in the space satisfying the following: $$ \mu(A_1) = \max \{\mu(A)\}, \\ \mu(A_2) = \min ...
0 votes
1 answer
42 views
Is change of variables formula for signed measures valid also for functions with infinite integral?
Let $\mu$ be a signed measure on $X$ with Jordan decomposition $\mu^+-\mu^-$, $\pi:X\rightarrow Y$ a measurable map, $\pi_\#\mu$ the pushforward measure of $\mu$ with respect to $\pi$. If $f:Y\...
1 vote
1 answer
41 views
Are two Radon signed measures agreeing on compacts equal?
Let $X$ be a Hausdorff space and $\mu,\nu:\mathfrak{B}(X)\to \mathbb{R}$ two Radon signed measure (that is, $|\mu|$ and $|\nu|$ are Radon measures). If $\mu (K)=\nu (K)$ for all compacts $K\subseteq X$...
0 votes
0 answers
77 views
Showing that $\nu(E) := \int_E f \,d\mu$ is a signed measure when $f$ is extended $\mu$-integrable
Let $(X,\mathcal{M},\mu)$ be a measure space and let $f:X \to [-\infty,\infty]$ be an extended $\mu$-integrable function (i.e. $f$ is measurable and at least one of $\int f^{+} \,d\mu$ and $\int f^{-} ...
0 votes
0 answers
47 views
If $\mu_n {\rightharpoonup}\mu$, then under what conditions $|\mu_n - \mu | {\rightharpoonup} 0$?
Let $(X,\mathcal{B})$ be a measurable space where $X \subseteq \mathbb{R}^d$,compact, $\mathcal{B}$ is the Borel sigma algebra, $\mu$ is a finite signed measure. Let $\left\langle \mu_n\right\rangle_{...
2 votes
0 answers
74 views
Quasi-probability density functions and vanishing expectation
I am interested in the properties of smooth quasi-probability density functions. In two dimensions, these are smooth functions $\rho(x,y):\, \mathbb{R}^2\to \mathbb{R}$ that satisfy the conditions \...
3 votes
0 answers
80 views
Signed Measures and Radon-Nikodym Theorem with Total Variation Measure
This is a question from Richard Bass, Real Analysis for Graduate Students. If $\mu$ is a signed measure on $(X,A)$ and $|\mu|$ is the total variation measure, prove that there exists a real-valued ...
1 vote
0 answers
72 views
Prove: $F:M(X,\mathscr{A},\mathbb{R})\to\mathbb{R}$ defined by $F(\mu)=\int fd\mu$ is a linear functional. [closed]
I need to prove the following result: Remark 4.30$\quad$ Let $M(X,\mathscr{A},\mathbb{R})$ be the collection of all finite signed measures on $(X,\mathscr{A})$. Let $B(X,\mathscr{A},\mathbb{R})$ be ...
2 votes
1 answer
104 views
Signed measure and bounded total variation on algebras
Let $X$ be a compact Hausdorff second countable topological space. Let $\mathcal{B}$ a countable basis of the topology of $X$, which we can assume to be closed under finite unions and intersections, ...
1 vote
0 answers
56 views
Why does $\mu\mapsto\int fd\mu$ defines a linear functional on $M(X,\mathscr{A},\mathbb{R})$?
I am self-studying signed measure.I got stuck on the following remark: Remark$\quad$ Let $M(X,\mathscr{A},\mathbb{R})$ be the collection of all finite signed measures on $(X,\mathscr{A})$. Then the ...
2 votes
1 answer
122 views
Question About Signed Measures
I am self-studying signed measure, and I come across the following construction: Let $\mu$ be a signed measure on the measurable space $(X,\mathscr{A})$, and let $A$ be a subset of $X$ that belongs ...
2 votes
0 answers
42 views
Prove: Define $\nu$ on $\mathscr{A}$ by $\nu(A) = \int_Afd\mu$. Then $\nu$ is a signed measure on $(X,\mathscr{A})$.
I am self-studying measure theory and I come across the following question: Prove: Let $(X,\mathscr{A},\mu)$ be a measure space, let $f$ belong to $\mathscr{L}^1(X,\mathscr{A},\mu,\mathbb{R})$, and ...