Submartingale Condition for Weak Convergence for Semi-Markov Processes
Vitaliy Golomoziy
TL;DR
This paper extends the classical Strook–Varadhan submartingale condition for weak convergence to semi-Markov processes by embedding the process in a Markov renewal framework. It shows that a straightforward discrete-time restatement is insufficient and introduces an additional condition requiring uniformly vanishing expected waiting times after short horizons, yielding tightness in the Skorokhod space $D[0,\infty)$. A counterexample demonstrates the necessity of the extra condition, and the authors develop a space–time scaling approach to verify the condition in practice, including a criterion expressed via holding-time tails. The results advance the theory of weak convergence for semi-Markov processes and inform practical approximation schemes via space–time scaling in applications.
Abstract
In this paper, we consider a modified version of a well-known submartingale condition fortheweak convergence of probabilitymeasures, adapted to the semi-Markov case. In this setting, it is convenient to work with an embedded Markov chain and the filtration generated by jump times. We demonstrate that a straightforward restatement of the classical result is not valid, and that an additional condition is required.
