Bismut-Elworthy-Li Formulae for Forward-Backward SDEs with Jumps and Applications
Jiagang Ren, Hua Zhang
TL;DR
Under nondegeneracy of the diffusion coefficient, the authors derive BEL-type gradient formulae for forward-backward SDEs with jumps using the lent particle method. They then apply these formulae to establish existence and uniqueness of solutions to nonlocal quasi-linear integral-PDEs differentiable in the spatial variable even when the initial data or coefficients are not differentiable. A sharp gradient bound $|\nabla_x Y(t,t,x)| \le C (T-t)^{-1/\beta} (1+|x|)^{\mu}$ for $\beta\in(1,2)$ is proved, and representation formulas connect the PDE solution to the FBSDE through $v(t,x)=Y(t,t,x)$ and $Z(\tau,t,x,u)=v(\tau,X(\tau,t,x)+\sigma(\tau,X(\tau,t,x))u)-v(\tau,X(\tau,t,x))$. This work bridges Malliavin calculus on Poisson space with nonlocal PDE theory and yields a robust approach for differentiable PDE solutions with rough data.
Abstract
Under nondegeneracy assumptions on the diffusion coefficients, we establish the derivative formulae of Bismut-Elworthy-Li's type for forward-backward stochastic differential equations with respect to Poisson random measure using the lent particle method created by Bouleau and Denis, which is not given before. Applying this formula, the existence and uniqueness of a solution of nonlocal quasi-linear integral partial differential equations, which are differentiable with respect to the space variable, are obtained, even if the initial datum and coefficients of this equation are not.
