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Maximum principle for state-constrained optimal control problems governed by quasilinear elliptic equations. (English) Zbl 0817.49025

The authors consider an optimal control problem governed by a quasilinear operator of elliptic type. They derive an optimality system of Pontryagin’s type. The result is important in several aspects: there is no stability condition (except of course for the qualified version of the result), the operator is quite general, and the proof combines ideas of renormalization, a general lemma about approximation with functions of “small” support, and Ekeland’s principle.

MSC:

49K20 Optimality conditions for problems involving partial differential equations
35J50 Variational methods for elliptic systems
93C20 Control/observation systems governed by partial differential equations