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Continuity of solutions to a basic problem in the calculus of variations

Francis Clarke — 2005

Annali della Scuola Normale Superiore di Pisa - Classe di Scienze

We study the problem of minimizing ∫ Ω F ( D u ( x ) ) d x over the functions u ∈ W 1 , 1 ( Ω ) that assume given boundary values φ on Γ : = ∂ Ω . The lagrangian F and the domain Ω are assumed convex. A new type of hypothesis on the boundary function φ is introduced: the (or upper) . This condition, which is less restrictive than the familiar bounded slope condition of Hartman, Nirenberg and Stampacchia, allows us to extend the classical Hilbert-Haar regularity theory to the case of semiconvex (or semiconcave) boundary data (instead of C 2 ). We...

Extensions of umbral calculus II: double delta operators, Leibniz extensions and Hattori-Stong theorems

Francis Clarke;  John Hunton;  Nigel Ray — 2001

Annales de l’institut Fourier

We continue our programme of extending the Roman-Rota umbral calculus to the setting of delta operators over a graded ring E * with a view to applications in algebraic topology and the theory of formal group laws. We concentrate on the situation where E * is free of additive torsion, in which context the central issues are number- theoretic questions of divisibility. We study polynomial algebras which admit the action of two delta operators linked by an invertible power series, and make related constructions...

Feedback in state constrained optimal control

Francis H. Clarke;  Ludovic Rifford;  R. J. Stern — 2002

ESAIM: Control, Optimisation and Calculus of Variations

An optimal control problem is studied, in which the state is required to remain in a compact set S . A control feedback law is constructed which, for given ε > 0 , produces ε -optimal trajectories that satisfy the state constraint universally with respect to all initial conditions in S . The construction relies upon a constraint removal technique which utilizes geometric properties of inner approximations of S and a related trajectory tracking result. The control feedback is shown to possess a robustness...

Feedback in state constrained optimal control

Francis H. Clarke;  Ludovic Rifford;  R. J. Stern — 2010

ESAIM: Control, Optimisation and Calculus of Variations

An optimal control problem is studied, in which the state is required to remain in a compact set . A control feedback law is constructed which, for given ε > 0, produces -optimal trajectories that satisfy the state constraint universally with respect to all initial conditions in . The construction relies upon a constraint removal technique which utilizes geometric properties of inner approximations of and a related trajectory tracking result. The control feedback is shown to possess a robustness...

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