The truncated EM method for stochastic differential delay equations with variable delay

TL;DR

This paper develops a truncated Euler-Maruyama method for stochastic differential delay equations with variable delay, proving strong convergence and stability under relaxed conditions, and demonstrating its effectiveness through numerical examples.

Contribution

It introduces a new truncated EM method for SDDEs with variable delay, achieving better convergence order under more general conditions.

Findings

Strong convergence order 1/2 under global conditions

Preserves mean-square and H-infinity stability

Numerical examples confirm theoretical results

Abstract

This paper mainly investigates the strong convergence and stability of the truncated Euler-Maruyama (EM) method for stochastic differential delay equations with variable delay whose coefficients can be growing super-linearly. By constructing appropriate truncated functions to control the super-linear growth of the original coefficients, we present a type of the truncated EM method for such SDDEs with variable delay, which is proposed to be approximated by the value taken at the nearest grid points on the left of the delayed argument. The strong convergence result (without order) of the method is established under the local Lipschitz plus generalized Khasminskii-type conditions and the optimal strong convergence order $1/2$ can be obtained if the global monotonicity with U function and polynomial growth conditions are added to the assumptions. Moreover, the partially truncated EM method is proved to preserve the mean-square and H_\infty stabilities of the true solutions. Compared with the known results on the truncated EM method for SDDEs, a better order of strong convergence is obtained under more relaxing conditions on the coefficients, and more refined technical estimates are developed so as to overcome the challenges arising due to variable delay. Lastly, some numerical examples are utilized to confirm the effectiveness of the theoretical results.