On the Nonexistence of Continuous Immersions for Discrete-time Systems
For researchers in dynamical systems and control theory, this paper provides theoretical limitations on linearization of discrete-time nonlinear systems, extending known continuous-time obstructions.
This paper extends prior results on the nonexistence of linear immersions for continuous-time systems to discrete-time systems, showing that discrete-time dynamics with multiple omega-limit sets cannot be immersed into finite-dimensional linear systems with continuous one-to-one mappings. The results are also generalized to alpha-limit sets.
Understanding when linear immersions of nonlinear dynamical systems exist is important since such immersions allow us to leverage the rich tools of linear system theory to analyze nonlinear dynamics. Recently, Liu et al. (2023) showed that continuous-time dynamical systems that admit countably many but more than one omega-limit sets cannot be immersed into finite dimensional linear systems with a one-to-one and continuous mapping. In this paper, we extend these results to discrete-time dynamics and show that similar obstructions exist also in discrete time. We further consider a generalization involving alpha-limit sets. Several examples are provided to demonstrate the results.