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Maximisation and minimisation on classes of rearrangements*

Published online by Cambridge University Press:  14 November 2011

G. R. Burton
Affiliation:
School of Mathematical Sciences, University of Bath, Claverton Down, Bath BA2 7AY, U.K.
J. B. McLeod
Affiliation:
Department of Mathematics, University of Pittsburgh, Pittsburgh PA 15260, U.S.A.

Synopsis

Maximisation and minimisation of the Dirichlet integral of a function vanishing on the boundary of a bounded domain are studied, subject to the constraint that the Laplacean be a rearrangement of a given function. When the Laplacean is two-signed, non-existence of minimisers is proved, and some information on the limits of minimising sequences obtained; this contrasts with the known existence of minimisers in the one-signed case. When the domain is a ball and the Laplacean is one-signed, maximisers and minimisers are shown to be radial and monotone. Existence of maximisers is proved subject additionally to a finite number of linear constraints, with particular reference to ideal fluid flows of prescribed angular momentum in a disc.

Type
Research Article
Copyright
Copyright © Royal Society of Edinburgh 1991

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