On the Computational Complexity of Limit Cycles in Dynamical Systems
Abstract
We study the Poincare-Bendixson theorem for two-dimensional continuous dynamical systems in compact domains from the point of view of computation, seeking algorithms for finding the limit cycle promised by this classical result. We start by considering a discrete analogue of this theorem and show that both finding a point on a limit cycle, and determining if a given point is on one, are PSPACE-complete. For the continuous version, we show that both problems are uncomputable in the real complexity sense; i.e., their complexity is arbitrarily high. Subsequently, we introduce a notion of an "approximate cycle" and prove an "approximate" Poincar\'e-Bendixson theorem guaranteeing that some orbits come very close to forming a cycle in the absence of approximate fixpoints; surprisingly, it holds for all dimensions. The corresponding computational problem defined in terms of arithmetic circuits is PSPACE-complete.
Cite
@article{arxiv.1511.07605,
title = {On the Computational Complexity of Limit Cycles in Dynamical Systems},
author = {Christos H. Papadimitriou and Nisheeth K. Vishnoi},
journal= {arXiv preprint arXiv:1511.07605},
year = {2015}
}