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Acyclic inductive spectra of Fréchet spaces

Jochen Wengenroth (1996)

Studia Mathematica

We provide new characterizations of acyclic inductive spectra of Fréchet spaces which improve the classical theorem of Palamodov and Retakh. It turns out that acyclicity, sequential retractivity (defined by Floret) and further strong regularity conditions (introduced e.g. by Bierstedt and Meise) are all equivalent. This solves a problem that was folklore since around 1970. For inductive limits of Fréchet-Montel spaces we obtain even stronger results, in particular, Grothendieck's problem whether...

Addendum to: "Sequences of 0's and 1's" (Studia Math. 149 (2002), 75-99)

Johann Boos, Toivo Leiger (2005)

Studia Mathematica

There is a nontrivial gap in the proof of Theorem 5.2 of [2] which is one of the main results of that paper and has been applied three times (cf. [2, Theorem 5.3, (G) in Section 6, Theorem 6.4]). Till now neither the gap has been closed nor a counterexample found. The aim of this paper is to give, by means of some general results, a better understanding of the gap. The proofs that the applications hold will be given elsewhere.

Adjoint bi-continuous semigroups and semigroups on the space of measures

Bálint Farkas (2011)

Czechoslovak Mathematical Journal

For a given bi-continuous semigroup ( T ( t ) ) t 0 on a Banach space X we define its adjoint on an appropriate closed subspace X of the norm dual X ' . Under some abstract conditions this adjoint semigroup is again bi-continuous with respect to the weak topology σ ( X , X ) . We give the following application: For Ω a Polish space we consider operator semigroups on the space C b ( Ω ) of bounded, continuous functions (endowed with the compact-open topology) and on the space M ( Ω ) of bounded Baire measures (endowed with the weak * -topology)....

Affine Baire functions on Choquet simplices

Miroslav Kačena, Jiří Spurný (2011)

Open Mathematics

We construct a metrizable simplex X such that for each n ɛ ℕ there exists a bounded function f on ext X of Baire class n that cannot be extended to a strongly affine function of Baire class n. We show that such an example cannot be constructed via the space of harmonic functions.

Algunos nuevos resultados sobre el teorema de la gráfica cerrada.

Manuel Valdivia (1979)

Revista Matemática Hispanoamericana

Para varios espacios localmente separados, damos aplicaciones lineales no continuas con gráficas cerradas. Uno de los resultados obtenidos contiene el teorema de Mahowald como corolario [7]. Si ε es una clase de espacios localmente convexos separados, estable para límites inductivos y conteniendo los espacios de dimensiones finitas, sea εr la clase de todos los espacios localmente convexos separados tales que si E ∈ ε, F ∈ εr y f es una aplicación lineal de E en F con gráfica cerrada, entonces f...

Almost demi Dunford--Pettis operators on Banach lattices

Hedi Benkhaled (2023)

Commentationes Mathematicae Universitatis Carolinae

We introduce new concept of almost demi Dunford–Pettis operators. Let E be a Banach lattice. An operator T from E into E is said to be almost demi Dunford–Pettis if, for every sequence { x n } in E + such that x n 0 in σ ( E , E ' ) and x n - T x n 0 as n , we have x n 0 as n . In addition, we study some properties of this class of operators and its relationships with others known operators.

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