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Local observability of nonlinear systems. (English) Zbl 0877.93010
Summary: A necessary and sufficient condition for local observability of analytic systems is presented. For smooth systems this condition is only sufficient, but it is still weaker than the Hermann-Krener rank condition. It is expressed with the language of ideals of germs of analytic or smooth functions and real radicals of such ideals. The condition may be practically checked in many cases.

MSC:
93B07Observability
93B29Differential-geometric methods in systems theory (MSC2000)