Open Access
April, 1987 A Large Deviations Principle for Small Perturbations of Random Evolution Equations
Carol Bezuidenhout
Ann. Probab. 15(2): 646-658 (April, 1987). DOI: 10.1214/aop/1176992163
Abstract

We prove a result for small random perturbations of random evolution equations analogous to the Ventsel-Freidlin result on small perturbations of dynamical systems. In particular, we derive large deviations estimates and indicate how they can be used to prove an exit result. The processes we study are governed by equations of the form $dx^\varepsilon(t) = b(x^\varepsilon(t), y(t)) dt + \sqrt \varepsilon \sigma(x^\varepsilon(t)) dw(t)$, where $x^0$ is already a random process. The results include the case where $y$ is an $n$-state Markov process. In the special case $\sigma \equiv Id$, the proof of the estimates is a consequence of a generalization of the "contraction principle" for large deviations: We give sufficient conditions on a continuous function $F$, which ensure that if $\{X_\varepsilon: \varepsilon > 0\}$ satisfies a large deviations principle, then so does $\{F(X_\varepsilon, Y): \varepsilon > 0\}$, where $Y$ is independent of $\{X_\varepsilon: \varepsilon > 0\}$.

Copyright © 1987 Institute of Mathematical Statistics
Carol Bezuidenhout "A Large Deviations Principle for Small Perturbations of Random Evolution Equations," The Annals of Probability 15(2), 646-658, (April, 1987). https://doi.org/10.1214/aop/1176992163
Published: April, 1987
Vol.15 • No. 2 • April, 1987
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