Characterizations of tauberian operators and other semigroups
Manuel González Ruiz, Víctor M. Onieva Aleixandre (1988)
Extracta Mathematicae
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Manuel González Ruiz, Víctor M. Onieva Aleixandre (1988)
Extracta Mathematicae
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Pietro Aiena, Manuel González, Antonio Martínez-Abejón (2001)
Bollettino dell'Unione Matematica Italiana
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In questo lavoro, motivati dalla teoria di Fredholm in spazi di Banach e dalla cosiddetta teoria degli ideali di operatori nel senso di Pietsch, viene definito un nuovo concetto di semigruppo di operatori. Questa nuova definizione include quella di molte classi di operatori già studiate in letteratura, come la classe degli operatori di semi-Fredholm, quella degli operatori tauberiani ed altre ancora. Inoltre permette un nuovo ed unificante approccio ad una serie di problemi in teoria...
Manuel González (1990)
Extracta Mathematicae
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Tauberian operators, which appeared in response to a problem in summability [GaW, KW] have found application in several situations: factorization of operators [DFJP], preservation of isomorphic properties of Banach spaces [N, NR], equivalence between the Radon-Nikodym property and the Krein-Milman property [Sch], and generalized Fredholm operators [Ta, Y]. This paper is a survey of the main properties and applications of Tauberian operators.
M. González, A. Martínez-Abejón (1993)
Extracta Mathematicae
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Upper semi-Fredholm operators and tauberian operators in Banach spaces admit the following perturbative characterizations [6], [2]: An operator T: X --> Y is upper semi-Fredholm (tauberian) if and only if for every compact operator K: X --> Y the kernel N(T+K) is finite dimensional (reflexive). In [7] Tacon introduces an intermediate class between upper semi-Fredholm operators and tauberian operators, the supertauberian operators, and he studies this class using non-standard...
Manuel González, Antonio Martinón (1990)
Extracta Mathematicae
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Beatriz Hernando (1990)
Extracta Mathematicae
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Manuel González, Antonio Martínez-Abejón (1997)
Extracta Mathematicae
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Here we present and example and some results suggesting that there is no infinite-dimensional reflexive subspace Z of L1 ≡ L1[0,1] such that the quotient L1/Z is isomorphic to a subspace of L1.
Manuel González, Antonio Martinón (1990)
Extracta Mathematicae
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