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Higher order Wirtinger inequalities

Published online by Cambridge University Press:  14 November 2011

Kurt Kreith
Affiliation:
University of California, Davis, Calif., U.S.A.
Charles A. Swanson
Affiliation:
University of British Columbia, Vancouver, Canada

Synopsis

Wirtinger-type inequalities of order n are inequalities between quadratic forms involving derivatives of order kn of admissible functions in an interval (a, b). Several methods for establishing these inequalities are investigated, leading to improvements of classical results as well as systematic generation of new ones. A Wirtinger inequality for Hamiltonian systems is obtained in which standard regularity hypotheses are weakened and singular intervals are permitted, and this is employed to generalize standard inequalities for linear differential operators of even order. In particular second order inequalities of Beesack's type are developed, in which the admissible functions satisfy only the null boundary conditions at the endpoints of [a, b] and b does not exceed the first systems conjugate point (a) of a. Another approach is presented involving the standard minimization theory of quadratic forms and the theory of “natural boundary conditions”. Finally, inequalities of order n + k are described in terms of (n, n)-disconjugacy of associated 2nth order differential operators.

Type
Research Article
Copyright
Copyright © Royal Society of Edinburgh 1980

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