This section presents some definitions in order to establish a basic algebraic framework for nonlinear state estimation.This framework is taken from the work of Fliess et al. (2008).We recommend any interested reader to check this paper and the references cited therein in order to have a detailed description of this differential algebraic setting.The algebraic method for nonlinear estimation is an extension of algebraic techniques for linear closed-loop parametric estimation (Fliess and Sira-Ramírez, 2003,
