What is it about?
Linear response theory provides a powerful framework for understanding the impact of perturbations on a given dynamical system. It investigates whether the resulting changes in the system’s statistical properties are differentiable with respect to the perturbations. This article studies an inverse problem related to the linear response, called Optimal Response, in which one searches for the optimal perturbation in order to change the statistical properties of the system in a wanted direction. We study this problem in a class of random dynamical system defined by a stochastic differential equation on a non-compact space, using a functional analytic tool known as the transfer operator. In particular we consider the problem of finding the optimal response in order to change as much as possible the average of a given observable, showing existence and uniqueness results for the solutions of this problem. We also show algorithms to approximate the optimal solution.
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Why is it important?
This theory is widely applied in physics, engineering, climate science, and statistical mechanics to analyse how systems evolve under external influences. Optimal response finds many applications, including climate sciences, for example in finding out which initial climatic actions can produce the greatest change in average temperature.
Perspectives
Writing this article was a great pleasure, and the respective collaboration has been fruitful and enlightening. This problem of optimal response is relatively new and it is a very relevant question in many applications. According to my conversations with a renowned climatologist, I am confident that this article has potential of being applicable to climate problems with little adaptation. Additionally, it is first of its kind to address this problem on SDE defined in multidimensional non-compact setting, therefore it has great potential of invoking more research on the problem.
Sakshi Jain
Monash University
Read the Original
This page is a summary of: Optimal response for stochastic differential equations by local kernel perturbations, Chaos An Interdisciplinary Journal of Nonlinear Science, July 2025, American Institute of Physics,
DOI: 10.1063/5.0265433.
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