Approximation methods for piecewise deterministic Markov processes and their costs

Scand Actuar J. 2019 Jan 9;2019(4):308-335. doi: 10.1080/03461238.2018.1560357. eCollection 2019.

Abstract

In this paper, we analyse piecewise deterministic Markov processes (PDMPs), as introduced in Davis (1984). Many models in insurance mathematics can be formulated in terms of the general concept of PDMPs. There one is interested in computing certain quantities of interest such as the probability of ruin or the value of an insurance company. Instead of explicitly solving the related integro-(partial) differential equation (an approach which can only be used in few special cases), we adapt the problem in a manner that allows us to apply deterministic numerical integration algorithms such as quasi-Monte Carlo rules; this is in contrast to applying random integration algorithms such as Monte Carlo. To this end, we reformulate a general cost functional as a fixed point of a particular integral operator, which allows for iterative approximation of the functional. Furthermore, we introduce a smoothing technique which is applied to the integrands involved, in order to use error bounds for deterministic cubature rules. We prove a convergence result for our PDMPs approximation, which is of independent interest as it justifies phase-type approximations on the process level. We illustrate the smoothing technique for a risk-theoretic example, and compare deterministic and Monte Carlo integration.

Keywords: 60J25; 65D32; 91G60; Risk theory; dividend maximisation; phase-type approximations; piecewise deterministic Markov process; quasi-Monte Carlo methods.

Grants and funding

Peter Kritzer P. Kritzer is supported by the Austrian Science Fund (FWF): Project F5506-N26, which is part of the Special Research Program ‘Quasi-Monte Carlo Methods: Theory and Applications’. P. Kritzer is partially supported by the National Science Foundation (NSF) [grant number DMS-1638521] to the Statistical and Applied Mathematical Sciences Institute. P. Kritzer, G. Leobacher, and M. Szölgyenyi gratefully acknowledge the partial support of the Erwin Schrödinger International Institute for Mathematics and Physics (ESI) in Vienna under the thematic programme ‘Tractability of High Dimensional Problems and Discrepancy’. G. Leobacher is supported by the Austrian Science Fund (FWF): Project F5508-N26, which is part of the Special Research Program ‘Quasi-Monte Carlo Methods: Theory and Applications’. M. Szölgyenyi is supported by the AXA Research Fund grant ‘Numerical Methods for Stochastic Differential Equations with Irregular Coefficients with Applications in Risk Theory and Mathematical Finance’ and supported by the Vienna Science and Technology Fund (WWTF): Project MA14-031.