Questions tagged [random-walk]
For questions on random walks, a mathematical formalization of a path that consists of a succession of random steps.
2,564 questions
3 votes
1 answer
60 views
Convergence of Random Walk and Bounded Martingals
First, consider a symmetric random walk $X_n := Y_1 + \dots + Y_n$, with $P(Y_k = \pm 1) = \frac{1}{2}$ for all $k \in \mathbb{N}$. For $c > 0$ define the stopping time $T_c := \min \{n \geq 0 \,|\,...
0 votes
0 answers
81 views
How to derive the distribution of a 2D random walk?
A few years prior, an acquaintance of mine tackled a problem inspired by something in our statistics class, which basically was the idea of "what is the expected distance from the starting point ...
2 votes
0 answers
56 views
References for a probability law [closed]
Consider a symmetric simple random walk starting at $0$ and denote by $p_{n,k}$ the probability the walk occupes $k$ at time $n$. Denote also $q_n=\left(q_{n,k}\right)_{k\geq 0}$ defined by $$ q_{n,k}=...
3 votes
1 answer
106 views
Derivation of Diffusion Equation in 1-D
I am trying to rigorously derive the diffusion equation, given by $$ \frac{\partial u}{\partial t} = D\,\frac{\partial^2 u}{\partial x^2}, \qquad D = \frac{h^2}{2\tau}. $$ from a simple one-...
2 votes
0 answers
84 views
Reversibility of a random walk
Let a random walk on a graph $G=(V,E)$ be characterized by the transition matrix $P$. The usual discrete random walk process is: \begin{equation} p^{t+1}= p^{t} P, \end{equation} where $p^{t}$ is a ...
1 vote
0 answers
48 views
Gibbs measure is the distribution of a $k$-step Markov chain if the potential depends on the first $k$ coordinates
My question came from this paper by Lalley (p.g. 2114) where he showed that the hitting/harmonic measure from finite ranged random walk on free groups is a Gibbs state. Let $(\Lambda_+,\sigma)$ be a ...
0 votes
0 answers
35 views
Markov mixing and coupling confusion: example in Markov Chains and Mixing times by Levin and Peres
Example 14.9 (p. 205) in Markov Chains and Mixing times describes a state space of $n$ $+$ or $-$ cards. The chain moves by interchanging two cards at random (side question: why is this a complete ...
6 votes
1 answer
620 views
Median wealth after repeated iterations of multiplicative game?
I start with \$1. After one iteration of a game, one of the following $m$ outcomes occurs: With probability $p_1$, my wealth multiplies by $r_1$; With probability $p_2$, my wealth multiplies by $r_2$;...
1 vote
0 answers
64 views
Optimal Stopping Random Walk
On a given probability space $(\Omega, \mathcal{F}, \mathbb{P})$, consider the simple symmetric random walk $$ S_0 = 0, \qquad S_n = \sum_{j=1}^n \xi_j, \quad n \in \mathbb{N}, $$ where $(\xi_1, \xi_2,...
-1 votes
1 answer
57 views
Random walk on surface of a cylinder [closed]
I am looking into random walk on top of $3D$ surfaces, say along the surface of a cylinder when surface is distributed into equidistance lattice points. I can't find much of it online. Anywhere I can ...
0 votes
0 answers
57 views
Will hitting time of a random walk increase if it starts to occasionally get lazier?
Consider a simple lazy random walk on 0, 1, 2, ..., $n$. It starts at $k$ and at every step gets +1 or -1 with equal probabilities $p$, or stays where it is with probability $1-2p$. Except for when ...
5 votes
0 answers
77 views
Reference for triviality of tail sigma algebra for the continuous time random walk
Let $(X_t)_{t \ge 0}$ be a continuous-time random walk in $\mathbb Z^d$, it has an exponential holding time of rate 1 and then chooses where to jump uniformly at random from its $2d$ neighbours. I am ...
7 votes
2 answers
171 views
Expected time to exit first quadrant in 2D random walk
Let $W \subseteq \mathbb{R}^2$ be a finite set of vectors, $ P$ be a probability distribution on $W$, and $V_0\in \mathbb{R}^2$ (for simplicity it suffices to consider $V_0$ where both coordinates are ...
1 vote
1 answer
112 views
Why doesn't this integrated random walk admit a density in $\mathbb{R}^4$?
In Chopin and Papaspiliopoulos' An Introduction to Sequential Monte Carlo, Section 2.4, Some Examples of State Space Models, an example is given of an integrated walk in $\mathbb{R}^4$, where the ...
0 votes
0 answers
74 views
Analysis of a binomial random walk and calculating its median
I'm currently analysing a binomial random walk which is given by $$\Delta\omega_t = \chi\left(\frac{W}{N} - \omega_t\right) + \eta_t\sqrt{\gamma}\ \omega_t$$ $$\omega_{t+1} = \omega_t + \Delta\omega_t$...