On lower-semicontinuity of variational integrals
Šverák, Vladimír
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Šverák, Vladimír
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Krzysztof Chełmiński, Agnieszka Kałamajska (2006)
ESAIM: Control, Optimisation and Calculus of Variations
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We consider the lower semicontinuous functional of the form where satisfies a given conservation law defined by differential operator of degree one with constant coefficients. We show that under certain constraints the well known Murat and Tartar’s -convexity condition for the integrand extends to the new geometric conditions satisfied on four dimensional symplexes. Similar conditions on three dimensional symplexes were recently obtained by the second author. New conditions apply...
Vincenzo Nesi, Enrico Rogora (2007)
ESAIM: Control, Optimisation and Calculus of Variations
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The theory of compensated compactness of Murat and Tartar links the algebraic condition of rank- convexity with the analytic condition of weak lower semicontinuity. The former is an algebraic condition and therefore it is, in principle, very easy to use. However, in applications of this theory, the need for an efficient classification of rank- convex forms arises. In the present paper, we define the concept of extremal -forms and characterize them in the rotationally invariant...
Martin Kružík (2003)
Mathematica Bohemica
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We characterize generalized extreme points of compact convex sets. In particular, we show that if the polyconvex hull is convex in , , then it is constructed from polyconvex extreme points via sequential lamination. Further, we give theorems ensuring equality of the quasiconvex (polyconvex) and the rank-1 convex envelopes of a lower semicontinuous function without explicit convexity assumptions on the quasiconvex (polyconvex) envelope.
M. Bousselsal, H. Le Dret (2002)
Bollettino dell'Unione Matematica Italiana
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We compute the quasiconvex envelope of certain functions defined on the space of real matrices. These functions are basically functions of a quadratic form on . The quasiconvex envelope computation is applied to densities that are related to the James-Ericksen elastic stored energy function.