Conditions for existence and uniqueness of the inverse first-passage time problem applicable for L\'evy processes and diffusions

Abstract

For a stochastic process $(X_t)_{t\geq 0}$ we establish conditions under which the inverse first-passage time problem has a solution for any random variable $\xi >0$. For Markov processes we give additional conditions under which the solutions are unique and solutions corresponding to ordered initial states fulfill a comparison principle. As examples we show that these conditions include L\'evy processes with infinite activity or unbounded variation and diffusions on an interval with appropriate behavior at the boundaries. Our methods are based on the techniques used in the case of Brownian motion and rely on discrete approximations of solutions via $\Gamma$-convergence from [3] (Anulova 1980) and [12] (Chen et. al. 2011) combined with stochastic ordering arguments adapted from [34] (Klump and Kolb 2023).