Questions tagged [pr.probability]
Theory and applications of probability and stochastic processes: e.g. central limit theorems, large deviations, stochastic differential equations, models from statistical mechanics, queuing theory.
2
votes
1answer
39 views
Expectation of the exitpoint distance for the symmetric random walk
Let $\nu(x)$ be a symmetric probability measure with respect to the origin on $x\in[-1,1]$ such that $\nu(\{0\})\neq 1$.
Consider a random walk started at $S_0=0$, denoted $S_n=X_1+\dotsb+X_n$, ...
1
vote
0answers
31 views
Optimizing a determinant
Any vector is assumed to be a column vector by default. Suppose $f(\mathbf{x})$ is the $d$-dimensional standard Gaussian density. I am interested in the following optimization problem:
$$
\max_g ~\...
1
vote
1answer
48 views
Expected determinant of random symmetric matrix with different Gaussian distributions of the diagonal and non-diagonal elements
Consider a random matrix $A \in \mathbb{R}^{N \times N}$ where the elements are random gaussian variables. The mean and variance of the elements are different on the diagonal and the off-diagonal:
$\...
0
votes
0answers
20 views
Approximating Uniform/Arbitrary distribution with Gaussian mixture model?
so Silverman in his 1986 book mentioned about approximating distributions with Gaussian mixture models but he didn't go much further into the topic...I'm just wondering, say I'm given a N-dimensional ...
2
votes
1answer
60 views
How far away is $\max_{x: x \in \{0, \ldots, N\}} |W(x/N)|$ from $\max_{0 \leq t \leq 1} |W(t)|$ ($W(t)$ a Wiener process)?
How far away is
$$\max_{x: x \in \{0, \ldots, N\}} \left|W\left(\frac{x}{N}\right)\right|$$
from
$$\max_{0 \leq t \leq 1} |W(t)|$$
In other words, if you simulate a Wiener process over a finite ...
0
votes
0answers
37 views
$P(\max_{0 \leq t \leq 1} \|W(t)\| \leq x)$ has no closed-form expression… right?
$P(\max_{0 \leq t \leq 1} \|W(t)\| \leq x)$ shows up in a formula for computing $p$-values for a certain statistic, where $W(t)$ is a $d$-dimensional (standard) Wiener process. My advisor says the ...
1
vote
1answer
53 views
Maximum of sums of iid $X_i$'s where $X_i$ is the difference of two exponential r.v
Given $X_i = A_i - B_i$ where $A_i\sim \text{ Exp}(\alpha)$ and $B_i \sim \text{ Exp}(\lambda)$. Define $S_k = \sum_{i=1}^k X_i$ with $S_0 = 0$, and
$$M_n = \max_{1\leq k \leq n} S_k.$$
Is it ...
2
votes
2answers
108 views
Continuous embedding of the Skorohod space D(0,1) into L^2(0,1)
Let $D(0,1)$ be the Skorohod space with the Skorohod topology, i.e. the space of real-valued càdlàg-functions on $[0,1]$ with topology induced by the metric
$$d(f,g) = \inf_{\varphi \in \Lambda} \left\...
3
votes
0answers
87 views
Large deviation of random walk
1) Let $\{X_i\}_{i=1}^n$ be i.i.d. such that $\Pr(X_i=1 )=1-\Pr(X_i=-1)=p$. Define the random walk
$$
S_i = \sum_{j=1}^iX_j
$$
for $i=1,2,\ldots,n$.
I am looking for "good" exponential upper bounds ...
2
votes
1answer
60 views
Hoeffding's inequality for Hilbert space valued random elements
Suppose that $\mathbb H$ is a separable Hilbert space and $X_1,\ldots,X_n$ are independent zero mean $\mathbb H$-valued random elements such that $\|X_i\|\le s$ for each $1\le i\le n$, where $\|\cdot\|...
0
votes
1answer
93 views
A problem related to the comparison of two integer-valued random variables
Consider an urn containing red, blue and green balls (the situation is the same illustrated in this post).
Let $X$ be the non-negative, integer-valued random variable defined as the number of trials (...
2
votes
1answer
180 views
Complicated bound after using Stirling's approximation
I have this inequality $$\frac{1}{a}\exp\bigl\{-\frac{4}{h^2}\bigr\} \geq \frac{1}{f}$$ where $$ a \leq \Bigl(\pi^{d/2}\Gamma(\frac{1}{2}d+1)^{-1} + 1\Bigr) \left(\frac{h^{d+1}}{2} \Gamma \left(\frac{...
3
votes
2answers
112 views
Example of measure for some algebra over N
$\mathcal F$ is set of events. Can you give an example of some algebra $\mathcal A$ over $\mathbb N$ and a non-zero finitely additive measure $\mu$ on this algebra, which has a countably additive ...
1
vote
0answers
34 views
Extension of a result about measurable, additive functionals
Let $W$ be a set, and let $v$ be a finitely additive probability measure on $2^W$.
Equip $2^W$ with the Borel sigma-algebra $\mathcal{B}$ generated by the sub-basic sets of the form $\{a: w \in a\}$ ...
1
vote
4answers
199 views
Apply doubly stochastic matrix M to a probability vector, then entropy increases?
Consider a vector $p =(p_1,...p_n)$, $p_i>0$, $\sum p_i = 1$
and a matrix $M_{ij}$, which is doubly stochastic: $\sum_i M_{ij} = 1, \sum_j M_{ij} = 1, M_{ij} > 0$.
Question 1 Just apply ...
1
vote
0answers
21 views
How to formally relate the Parry Markov chain to a uniformly chosen bi-infinite path
I tried reformulating the comment after Proposition 10 in here as follows:
Let G be an aperiodic irreducible graph with adjacency matrix $A \in \mathcal{M}_d(\{0,1\})$ and associated Parry matrix $P$....
-4
votes
0answers
39 views
Matching Supply and Demand in an Uncertain World [closed]
i am trying to solve a question related to operations management when there is uncertainty. I am facing problem in determining the sample size and then what if the situation was not uncertain ? The ...
1
vote
0answers
43 views
Concrete Hanson-Wright inequality?
I'm working on a paper that requires bounding
$$\Pr\left[|\vec x^\top Q \vec y| >= t\right]$$ where $Q$ is a matrix (happens to be symmetric) and $\vec x,\vec y$ are iid real mean-zero subgaussian ...
2
votes
1answer
81 views
Measurability of C([0,1]) for the completion of the Wiener measure
Consider the completion $(\mathbb{R}^{[0,1]}, \mathcal{B}, \mu)$ of the Wiener measure on $\mathbb{R}^{[0,1]}$ (with the cylinder set $\sigma$-algebra).
Is the following true :
$C([0,1])\in \...
4
votes
3answers
102 views
Expected distance of nearest matching pair in the game of pairs
Recently I was playing several rounds of the game of pairs with my children. I was surprised that almost every time, one matching pair was adjacent (either next to each other in a row, or vertically). ...
0
votes
1answer
105 views
Shannon problem
Since a few days, I try in my research to model / formalize a source of Shannon a little weird, and I can't do it at all. First of all, I explain to you its operating principle and then I describe it ...
0
votes
0answers
125 views
Statistical models of functions
I did a quick literature search and found nothing on "statistical models of functions". Let me explain what I am looking for. Given the category of Sets and Function, we have arbitrary functions ...
0
votes
1answer
90 views
Expected values of two non-negative, integer-valued random variables related to an urn problem
Consider an urn containing $c$ distinguishable balls, $\alpha$ of which are red, $\beta$ of which are blue, and $\gamma$ of which are green, and $\alpha+\beta+\gamma=c$. We assume $\alpha,\beta,\gamma&...
-1
votes
1answer
36 views
Characterisation of a superset of the simplex
Does there exist a nice description of the following set:
\begin{equation}
A:=\left\lbrace x\in\mathbb{R}^{n}\ \colon\ 0< x_{i}-\bar{x}+\frac{1}{n}< 1\ \text{for} \ i=1,\dots,n\right\rbrace,
\...
4
votes
1answer
82 views
Is a Gaussian measure on a Hilbert space determined by the coarser topology induced by the covariance operator?
I have a basic question about Gaussian measures on a Hilbert space:
Let $\mu$ be a non-degenerate Gaussian measure on a Hilbert space $(H_0,\left\langle \cdot,\cdot \right\rangle_0)$. Then the ...
0
votes
0answers
11 views
Robust estimation of mean with total-variation uncertainty region
Let $\mathcal X$ be space and $P$ be a probability measure thereupon. Let $\mathcal B_{n,\delta}$ be the set of distributions $Q$ on $\mathcal X$ such that $D_f(Q\|\hat{P}_n) \le \delta$, where $D_f(\...
2
votes
0answers
62 views
How can we treat the generator of a discrete-time Markov chain as the generator of a Markov-jump process?
In the popular paper Weak Convergence and Optimal Scaling of Random Walk Metropolis Algorithms by Roberts, Gelman and Gilks, the authors state (see below) that "in the Skorokhod topology, it does not ...
3
votes
1answer
99 views
Is there a coupling that induces a given coupling via a transition kernel?
Let $X,Y$ be two measurable spaces, $\mu,\nu$ two probability measures on $X$, and $\kappa$ a transition kernel from $X$ to $Y$.
Define $\tilde\mu(dy)=\int_X\kappa(dy|x)\mu(dx)$ and $\tilde\nu(dy)=\...
11
votes
1answer
160 views
Mode of a sum of Bernoulli random variables
Let $S_n=\tau_1+\cdots+\tau_n$ be a sum of independent Bernoulli random variables such that $\mathbb{P}(\tau_i=1)=p_i$. Is it true that the mode of $S_n$ is either its mean rounded up or rounded down?
3
votes
0answers
105 views
Probability distribution from equidistribution - I
Pick a random pair $(a,b)\in\mathbb Z_n^2\backslash\{0,0\}$. Denote $N_r(a,b)$ to be minimum $\ell_r$ norm of vector $(x,y)$ as $(x,y)$ ranges over all non-zero integral solutions to $(x,y)\equiv t(a,...
2
votes
1answer
79 views
Probability density from standard domain
Pick $x+iy$ at random with respect to hyperbolic measure from $\{z:|z|\geq1,|\mathcal R(z)|\leq\frac12\}$. What does the probability distribution function of $\frac1{\sqrt y}$ look like?
3
votes
2answers
138 views
Is the covariance of squares always bounded from below by two times the covariance?
I came across the following inequality in one of my calculations ($X,Y$ are centered random variables):
$$\operatorname{E}(X^2Y^2)-\operatorname{E}(X^2)\operatorname{E}(Y^2) \geq 2 \operatorname{E}(...
2
votes
1answer
46 views
Generalization of Komlós–Major–Tusnády Approximation
The Komlós–Major–Tusnády Approximation (see Wikipedia) considers the sum of uniform variables in $(0,1)$. There are also version where instead the sum of equiprobable $0/1$ variables is used ($p=1/2$)....
4
votes
1answer
246 views
Expectation of exponential of a function of independent Rademacher r.v.'s involving the error function
Let $Z,Z'\in\{-1,1\}^n$ be two independent vectors of i.i.d. Rademacher r.v.'s, where $1\leq n \leq d$ are two integers ($d\gg 1$). I am trying to get an upper bound on
$$
\mathbb{E}_{ZZ'}\left[ \exp\...
0
votes
0answers
32 views
On the distribution of a random point of a poisson process
Let $T = \{t_i\}_{i=1}^\infty$ be the set of points in a Poisson point process on the positive half-axis with parameter $\lambda$, $I \in \mathbb{N}$ be a positive integral random variable with ...
3
votes
1answer
92 views
Why the Fisher information matrix is equal to the Hessian matrix of the Kullback–Leibler distance at the true parameter?
I'm reading 《Algebraic geometry and statistical learning theory》.My problem is why the Fisher information matrix is equal to the Hessian matrix of the Kullback–Leibler distance at the true parameter?...
3
votes
0answers
67 views
Exchangeable Bernoulli random variables with bounded summation implies negative correlation?
Let $\big\{X_1, X_2, ..., X_n \big\}$ be $n$ jointly exchangeable Bernoulli random variables, i.e., exchanging the order of these random variables does not change the joint distribution. If we know ...
3
votes
2answers
141 views
Probability of one species reaching zero before the other in a Markov process on a 2d lattice
$\textbf{Background}$: Say we've got a two-variable system of stochastic chemical reactions, with quantities $\vec{x}(t) = (x_1(t),x_2(t)) \in \mathbb{N}^2$ evolving according to the following system, ...
0
votes
0answers
47 views
Upper bound on expectation of product
I want to upper-bound the following quantity:
$$\mathbb{E}_Y\left[f(Y)g(Y)\right] $$
The idea would be to get something of the shape: $\mathbb{E}_Y[f(Y)]\cdot h(Y)$
where $h(Y)= j(\mathbb{E}_Y[k(g(Y))]...
-1
votes
0answers
60 views
Probability of the intersection of many events
Let $\{X_i\}_{i=1}^n$ be a sequence of $n$ i.i.d. Bernoulli random variables such that $\Pr\{X_i=1\}=1-\Pr\{X_i=0\}=p<1/2$.
I am interested in finding upper bounds on the probability
$$
\Pr\left\{\...
-1
votes
0answers
27 views
Gaussian Processes and the Measures of Finite Support Monad
Gaussian processes are defined on a domain, which is a set, and map each set element to a gaussian distribution over a target domain. I believe the idea is to model a function $f: X \rightarrow Y$ ...
-2
votes
0answers
46 views
Hitting times of Markov chains
I'm looking for references on the above topic. My particular interest is in discrete time, countable state space Markov processes. References can take any form (papers, books, notes etc.) and can ...
-2
votes
0answers
72 views
Tight bound on data binning problem
Consider dependent random variables $(X,Z)$ with joint pmf $p(x,z)$ on the finite alphabet set $\mathcal{X}\times\mathcal{Z}$.
Let $X^n, Z^n$ be $n$ i.i.d. repetitions of $(X, Z)$, i.e.,
$$p(x^n,z^n)=...
0
votes
0answers
107 views
Which probability distribution has the most outliers?
Let $k$ be a positive real number. Which probability distribution over $\mathbb R$ maximizes $P(|x-E(x)|>k\cdot \operatorname{std}(x))$?
0
votes
2answers
106 views
Distribution of the individual coordinates of a uniform random vector on a high-dimensional sphere
Let $X=(X_1,\ldots,X_n)$ be a random vector uniformly distributed on the $n$-dimensional sphere of radius $R > 0$. Intuitively, i think that for large $p$ every coordinate $X_i$ is normally ...
1
vote
0answers
32 views
If $(Y_n)_{n\in\mathbb N_0}$ and $(N_t)_{t\ge0}$ are stochastic processes, what is the filtration generated by $\left(Y_{N_t}\right)_{t\ge0}$?
Let
$(\Omega,\mathcal A)$ and $(E,\mathcal E)$ be measurable spaces
$(Y_n)_{n\in\mathbb N_0}$ be a $(E,\mathcal E)$-valued stochastic process on $(\Omega,\mathcal A)$
$(N_t)_{t\ge0}$ be a $\mathbb ...
9
votes
1answer
259 views
Maximal inequality for the average of i.i.d. random variables
Let $Z_i$ be i.i.d. random variables with $\mathbb{E}[Z_i] = 0$ and $\mathbb{E}|Z_i|^p< \infty$ for $p=1,2,3,\cdots$. I am looking for the following type of estimate if possible, and it is not like ...
1
vote
0answers
39 views
Is there a transient graph whose spectral dimension two?
Let $G = (V(G), E(G))$ be an infinite connected simple graph.
Let $((S_n)_n, (P^x)_{x \in V(G)})$ be the simple random walk on $G$.
Let $p_n (x,y) = P^x (S_n = y)$.
A spectral dimension of $G$ is ...
1
vote
0answers
53 views
Construction of Feller's pseudo-poisson process
Let
$(\Omega,\mathcal A,\operatorname P)$ be a probability space
$(E,\mathcal E)$ be a measurable space
$(Y_n)_{n\in\mathbb N_0}$ be a $(E,\mathcal E)$-valued time-homogeneous Markov chain on $(\...
0
votes
0answers
79 views
Supremum over all invariant Borel probability measures of the ergodic averages ratio of rates
Let $M$ a two-dimensional compact manifold and $f:M\to M$ a diffeomorphism $C^r$, $r\geq 2$ and $f(x,y)=(mx,\lambda y)$ where $m:M\to \mathbb{R}$ and $\lambda:M\to \mathbb{R}$ ,$\lambda<1<m$.
...
