- ▪E.D. Sontag, "On the observability of polynomial systems. I. Finite-time problems", SIAM J. Control Optim., vol. 17, no. 1, pp. 139–151, 1979. pdf
Abstract
Different notions of observability are compared for systems defined by polynomial difference equations. The main result states that, for systems having the standard property of (multiple-experiment initial-state) observability, the response to a generic input sequence is sufficient for final-state determination. Some remarks are made on results for nonpolynomial and/or continuous-time systems. An identifiability result is derived from the above.
- ▪E.D. Sontag, Y. Rouchaleau, "On discrete-time polynomial systems", Nonlinear Anal., vol. 1, no. 1, pp. 55–64, 1976. pdf
Abstract
Considered here are a type of discrete-time systems which have algebraic constraints on their state set and for which the state transitions are given by (arbitrary) polynomial functions of the inputs and state variables. The paper studies reachability in bounded time, the problem of deciding whether two systems have the same external behavior by applying finitely many inputs, the fact that finitely many inputs (which can be chosen quite arbitrarily) are sufficient to separate those states of a system which are distinguishable, and introduces the subject of realization theory for this class of systems.