Semiembeddings and semi-Fredholm operators
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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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 Ruiz, Víctor M. Onieva Aleixandre (1988)
Extracta Mathematicae
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Araujo, Jesús, Martinez-Maurica, J. (1990)
International Journal of Mathematics and Mathematical Sciences
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Manuel González, Antonio Martinón (1995)
Studia Mathematica
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Several operational quantities have appeared in the literature characterizing upper semi-Fredholm operators. Here we show that these quantities can be divided into three classes, in such a way that two of them are equivalent if they belong to the same class, and are comparable and not equivalent if they belong to different classes. Moreover, we give a similar classification for operational quantities characterizing lower semi-Fredholm operators.
D. Koehler, Peter Rosenthal (1970)
Studia Mathematica
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Charles E. Cleaver (1972)
Colloquium Mathematicae
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Alfonso Montes-Rodríguez, M. Carmen Romero-Moreno (2002)
Studia Mathematica
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We prove a Supercyclicity Criterion for a continuous linear mapping that is defined on the operator algebra of a separable Banach space ℬ. Our result extends a recent result on hypercyclicity on the operator algebra of a Hilbert space. This kind of result is a powerful tool to analyze the structure of supercyclic vectors of a supercyclic operator that is defined on ℬ. For instance, as a consequence of the main result, we give a very simple proof of the recently established fact that...
Akkouchi, Mohamed (2016-05-20T09:55:13Z)
Acta Universitatis Lodziensis. Folia Mathematica
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Manuel González, Antonio Martinón (1990)
Extracta Mathematicae
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Dehici, Abdelkader, Saoudi, Khaled (2007)
International Journal of Mathematics and Mathematical Sciences
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Beatriz Hernando (1990)
Extracta Mathematicae
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Vladimir Rakočević (1997)
Studia Mathematica
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An operator in a Banach space is called upper (resp. lower) semi-Browder if it is upper (lower) semi-Fredholm and has a finite ascent (resp. descent). An operator in a Banach space is called semi-Browder if it is upper semi-Browder or lower semi-Browder. We prove the stability of the semi-Browder operators under commuting Riesz operator perturbations. As a corollary we get some results of Grabiner [6], Kaashoek and Lay [8], Lay [11], Rakočević [15] and Schechter [16].