Gâteaux derivative,
weak derivative

The derivative of a functional or a mapping which — together with the Fréchet derivative (the strong derivative) — is most frequently used in infinite-dimensional analysis. The Gâteaux derivative at a point of a mapping from a linear topological space into a linear topological space is the continuous linear mapping that satisfies the condition
where as in the topology of (see also Gâteaux variation). If the mapping has a Gâteaux derivative at the point , it is called Gâteaux differentiable. The theorem on differentiation of a composite function is usually invalid for the Gâteaux derivative. See also Differentiation of a mapping.

References

[1]  R. Gâteaux,   "Sur les fonctionnelles continues et les fonctionnelles analytiques"  C.R. Acad. Sci. Paris Sér. I Math. , 157  (1913)  pp. 325–327
[2]  A.N. Kolmogorov,   S.V. Fomin,   "Elements of the theory of functions and functional analysis" , 1–2 , Graylock  (1957–1961)  (Translated from Russian)
[3]  W.I. [V.I. Sobolev] Sobolew,   "Elemente der Funktionalanalysis" , H. Deutsch , Frankfurt a.M.  (1979)  (Translated from Russian)
[4]  V.I. Averbukh,   O.G. Smolyanov,   "Theory of differentiation in linear topological spaces"  Russian Math. Surveys , 22 : 6  (1967)  pp. 201–258  Uspekhi Mat. Nauk , 22 : 6  (1967)  pp. 201–260


V.M. Tikhomirov


Comments

References

[a1]  M.S. Berger,   "Nonlinearity and functional analysis" , Acad. Press  (1977)

This text originally appeared in Encyclopaedia of Mathematics - ISBN 1402006098

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