Person:
Cobos Díaz, Fernando

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First Name
Fernando
Last Name
Cobos Díaz
URI
https://hdl.handle.net/20.500.14352/75635
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Matemáticas
Department
Análisis Matemático Matemática Aplicada
Area
Análisis Matemático
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1995 - 19992
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Author: Fernández-Martínez, Pedro × Subject: 519.6 ×

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Now showing 1 - 2 of 2
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    Interpolation of the measure of non-compactness by the real method
    (Studia Mathematica, 1999) Cobos Díaz, Fernando; Fernández-Martínez, Pedro; Martínez, Antón
    We investigate the behaviour of the measure of Iron-compactness of an operator under real interpolation. Our results refer to general Banach couples. An application to the essential spectral radius of interpolated operators is also given.
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    Dependence on Parameters in Interpolation Methods Associated to Polygons
    (Bollettino della Unione Matematica Italiana, 1995) Cobos Díaz, Fernando; Fernández-Martínez, Pedro
    A theorem due to S. Janson, P. Nilsson, J. Peetre and M. Zafran [Proc. Lond. Math. Soc., III. Ser. 48, 283-299 (1984; Zbl 0532.46046)] states that for a Banach couple A such that _(A) is not closed in _(A) the real interpolation spaces A_,q and A_,p coincide if and only if _ = _ and p = q. Here the analogous problem for N-tuples of Banach spaces is investigated. It is assumed that the N-tuple A satisfies a certain condition "(A) which ensures that the J- and the K-methods with respect to a polygon _ coincide. Also, it is assumed that _(A) is not closed in _(A). The authors prove the following results: (1) If P,Q 2 int _ and AP,p = AQ,q, then p = q. (2) If P, Q,R 2 int _ and AP,q = AQ,q = AR,q, then P, Q and R are affinely dependent.