🤖 AI Summary
This work establishes a rigorous mathematical foundation for the core properties of delay-based reservoir computing—separability, robustness, and fading memory. Drawing on control theory, the authors develop an analytical framework that formalizes separability and fading memory using function norms and links them to incremental input-to-state stability of time-delay systems. For the first time, this approach yields precise mathematical characterizations of both separability and fading memory, and derives an explicit lower bound on the separation distance for linear reservoirs, offering a computable design criterion. The methodology integrates tools from control theory, functional analysis, Fourier analysis, and stability theory for time-delay systems. Empirical validation on the NARMA10 benchmark and continuous-time system prediction tasks demonstrates its effectiveness, while also enabling highly minimal digital implementations.
📝 Abstract
Reservoir computing is a well-established approach for processing data with a much lower complexity compared to traditional neural networks. Despite two decades of experimental progress, the core properties of reservoir computing (namely separation, robustness, and fading memory) still lack rigorous mathematical foundations. This paper addresses this gap by providing a control-theoretic framework for the analysis of time-delay-based reservoir computers. We introduce formal definitions of the separation property and fading memory in terms of functional norms, and establish their connection to well-known stability notions for time-delay systems as incremental input-to-state stability. For a class of linear reservoirs, we derive an explicit lower bound for the separation distance via Fourier analysis, offering a computable criterion for reservoir design. Numerical results on the NARMA10 benchmark and continuous-time system prediction validate the approach with a minimal digital implementation.