L2

Generator of a Diffusion

Senior Quant · Stochastic Calculus

Question

Define the generator A\mathcal{A} of a diffusion dX=μdt+σdWdX = \mu\,dt + \sigma\,dW. Compute Af\mathcal{A}f for fC2(R)f \in C^2(\mathbb{R}). Show that f(Xt)0tAf(Xs)dsf(X_t) - \int_0^t \mathcal{A}f(X_s)\,ds is a local martingale (Dynkin's formula).