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3 votes
1 answer
85 views

What (continuous) stochastic processes have path measures that are absolutely continuous w.r.t. Wiener measure?

Suppose I have a stochastic process $\{Z_t\}_{t \in T}$ for which I know the sample paths to be a.s. continuous (we can also assume some usual stuff, such as $T$ a compact metric space, $Z$ having ...
3 votes
1 answer
439 views

Strong continuity of the Ornstein-Uhlenbeck operator

It's well known that the Ornstein-Uhlenbeck semigroup defined by $$ P_tf(x)=\int_{\mathbb{R}}f\left(xe^{-t}+\sqrt{1-e^{-2t}}z\right)\frac{e^{-z^2/2}}{\sqrt{2\pi}}\,dz $$ is not strongly continuous on ...
5 votes
1 answer
652 views

Proof of Pinelis (1992) - Banach space inequalities

I am reading Pinelis "An approach to inequalities for the distributions of infinite -dimensional martingales" and cannot follow his proof of Theorem 3: Let $(f_n)$ be a martingale in a separable ...
1 vote
0 answers
406 views

Quadratic Variation of a Martingale in Hlibert Spaces

I'm looking at a Martingale (actually a Martingale difference sequence), $$ M_n = \sum \delta M_n, $$ and I'd like to prove something about convergence. If Martingale is Hilbert space valued (...