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AN ALTERNATIVE APPROACH TO FRÉCHET DERIVATIVES

Published online by Cambridge University Press:  14 May 2020

SHANE ARORA
Affiliation:
School of Mathematics & Statistics, University of Sydney, NSW 2006, Australia e-mail: saro0188@uni.sydney.edu.au
HAZEL BROWNE
Affiliation:
School of Mathematics & Statistics, University of Sydney, NSW 2006, Australia e-mail: hbro4811@uni.sydney.edu.au
DANIEL DANERS
Affiliation:
School of Mathematics & Statistics, University of Sydney, NSW 2006, Australia e-mail: daniel.daners@sydney.edu.au
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Abstract

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We discuss an alternative approach to Fréchet derivatives on Banach spaces inspired by a characterisation of derivatives due to Carathéodory. The approach allows many questions of differentiability to be reduced to questions of continuity. We demonstrate how that simplifies the theory of differentiation, including the rules of differentiation and the Schwarz lemma on the symmetry of second-order derivatives. We also provide a short proof of the differentiable dependence of fixed points in the Banach fixed point theorem.

Type
Research Article
Copyright
© 2020 Australian Mathematical Publishing Association Inc.

Footnotes

Communicated by W. Moors

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