Questions tagged [stochastic-processes]
For questions about stochastic processes, for example random walks and Brownian motion.
16,782 questions
2 votes
0 answers
19 views
Joint measurability of the following random field
Consider a filtered probability space $(\Omega,\mathcal F,\mathbb F=\{\mathcal F_t\}_{t\in[0,T]},\mathbb P)$ where the filtration satisfies the standard assumptions. Let $X=(X_t)_{t\in[0,T]}$ be a ...
1 vote
0 answers
37 views
Stationary state in interacting particle systems
I am learning about interacting particle systems on lattices, and I am trying to clarify the logical order between two things: Detailed balance. For two configurations $C$ and $C'$, detailed balance ...
4 votes
3 answers
123 views
Some questions about Wiener process (Brownian motion).
My main research interest is PDE. I'm not very familiar with probability theory. Recently, I am reading a textbook related to probability interpretation of PDE. The part about Wiener process (Brownian ...
3 votes
0 answers
40 views
How to deal with Ito processes product with time delay?
I have the weight process $\omega_t$, and the asset price process $S_t$, both of them are Ito processes: $$\frac{d\omega_t}{\omega_t}=\mu^1_t\,dt+\sigma^1_tdW^1_t,\qquad \frac{dS_t}{S_t}=\mu^2_t\,dt+\...
1 vote
0 answers
27 views
Measurability of stochastic integrals appearing in local times
I am reading Le Gall's GTM book on Brownian motion and am confused about the proof of the generalized Ito formula in Chapter 9. Let me introduce the notations from that book: Let $X=M+V$ be a ...
1 vote
1 answer
56 views
Beginning time of i-th excursions of Wiener process is a stopping time?
Let $W$ be a Wiener process. Define its set of zeros as $C_{\omega}\equiv \{t\in \mathbb{R}_+: W_t(\omega)=0\}$. I know this set is closed, therefore, its complement $\mathbb{R}_+ \backslash C_{\omega}...
0 votes
0 answers
34 views
Optional sampling for a martingale at a hitting time
Let $M = (M_t)_{t\in\mathbb{N}}$ be a uniformly integrable martingale starting at $M_0 = 0$. By optional sampling for any stopping time $T$ almost surely \begin{equation*} \mathbb{E}[M_T|\mathscr{F}_0]...
4 votes
2 answers
325 views
Is there a way to solve linear 1st order ODEs with time-varying coefficients driven by geometric Brownian motion?
Let $X_t$ be a stochastic process satisfying, $$ dX_t = \mu(t)X_t dt + \sigma(t)X_t dW_t $$ where $W_t$ is a Brownian motion. Is there a way to solve the following for $y$? $$ y'(t) a(t) + y(t) b(t) + ...
3 votes
2 answers
326 views
How does the Black-Scholes equation handle drift? [duplicate]
I've been reading about the Black-Scholes formula on wikipedia and investopedia and it seems like a lot. My understanding is very limited, but naively it makes sense to me one would be able to assign ...
-1 votes
0 answers
49 views
Why do we need \rho (utilization)<1 in queuing theory?
I’m studying basic queueing theory, in particular a single–server queue with one arrival stream and one server (a G/G/1 type setup). Let A be the interarrival time with mean 𝔼(A), B be the service ...
3 votes
2 answers
117 views
Martingales convergence a.s.
Suppose we know that $P(X=1)=p, P(X=-1)=q=1-p$ We have a martingales a) $M_n = (\frac{q}{p})^{S_n}$, b) $M_n = S_n - n(p-q)$ where $S_n =\sum_{i=0}^n X_i$,( $X_i$ iid). How to show (in a simple way) ...
4 votes
0 answers
132 views
Stochastic exponential and martingales
I have a Question regarding the chapter 5.5.(Girsanov Theorem) of the Book "Brownian Motion,Martingales, and Stochastic Calculus" from le Gall. There is stated in Prop 5.21, that if D is a ...
1 vote
1 answer
50 views
Family of i.i.d. random variables is ergodic under shift
Let $(S, \mathcal{S})$ be some measurable state space, $\Omega := S^{\mathbb{N}_0}$, $X_i$ the coordinate maps, $\mathcal{A} := \sigma(X_0, X_1, \dots)$ and $\theta: \Omega \rightarrow \Omega, (x_0, ...
0 votes
0 answers
36 views
Solution to SDE as measurable function of initial value
In Schilling's "Brownian Motion", it is argued in Remark 21.24 that if the stochastic process $X^x$ is the solution to an SDE with initial value $x\in\mathbb{R}$, then it depends measurably ...
0 votes
0 answers
27 views
Convergence of transform of stochastic processes to transform of Brownian bridges
I have two sequences of independent stochastic processes $X^n$ and $Y^n$ that are known to converge weakly to the Brownian bridges $\mathcal X$ and $\mathcal Y$, respectively. For a continuous ...