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6 votes
0 answers
774 views

Relationship between the Itō formula for a Q-Wiener process and the Itō formula for a cylindrical Wiener process. A question on the trace term

Remark: Even when this question is about stochastic PDEs, it can be answered by someone who has no knowledge about probability theory or PDEs. I'm reading Stochastic Differential Equations in ...
0xbadf00d's user avatar
  • 167
3 votes
0 answers
231 views

I've found a representation of the Itō-Stratonovich correction term and don't understand the used notion of a "trace"

Consider a Stratonovich SPDE $$X_t=X_0+\int_0^tb(s,X_s)\:{\rm d}s+\int_0^t\sigma(s,X_s)\circ{\rm d}W_s\tag 1$$ in a separable $\mathbb R$-Hilbert space $H$ with $W$ being a $Q$-Wiener process on a ...
0xbadf00d's user avatar
  • 167
1 vote
1 answer
223 views

Stochastic integral is a continous or closed operator?

The Setup Let $\xi_t$ be a process adapted to the filtration $\mathfrak{F_t}$ of the semi-martinagale $X_t$, such that both are square integrable. Then is the map \begin{align} F_T: L^2(\mathfrak{...
ABIM's user avatar
  • 5,405
1 vote
1 answer
175 views

Stochastic operator on $\ell^1$ has dense range

Let $P:\ell^1(\mathbb{Z}^d) \rightarrow \ell^1(\mathbb{Z}^d)$ be given by $$(Pz)(x)=\sum_{y \tilde \ x} \frac{1}{2d} z(y)$$ where the tilde indicates that $y$ is a neighboured vertex of $x.$ I ...
BaoLing's user avatar
  • 329
1 vote
0 answers
134 views

Operator-valued stochastic integral and quadratic variation for operator-valued processes

Let $U$ be a separable $\mathbb R$-Hilbert space and $W$ be a $Q$-Wiener process on a complete and right-continuous filtered probability space. Let $H$ be a separable $\mathbb R$-Hilbert space and $X$ ...
0xbadf00d's user avatar
  • 167
1 vote
0 answers
159 views

Construction of the quadratic variation process in infinite dimensions

Let $H$ be a separable $\mathbb R$-Hilbert space $(e_n)_{n\in\mathbb N}$ be an orthonormal basis of $H$ $(\Omega,\mathcal A,\operatorname P)$ be a probability space $(\mathcal F_t)_{t\ge0}$ be a ...
0xbadf00d's user avatar
  • 167