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Displaying 381 – 400 of 659

Order properties of the space of finitely additive transition functions.

Gutman, A.E., Sotnikov, A.I. (2004)

Sibirskij Matematicheskij Zhurnal

Order properties of the space of strongly additive transition functions.

Sotnikov, A.I. (2005)

Sibirskij Matematicheskij Zhurnal

Order-bounded operators from vector-valued function spaces to Banach spaces

Marian Nowak (2005)

Banach Center Publications

Let E be an ideal of L⁰ over a σ-finite measure space (Ω,Σ,μ). For a real Banach space $(X, | | \cdot | |_{X})$ let E(X) be a subspace of the space L⁰(X) of μ-equivalence classes of strongly Σ-measurable functions f: Ω → X and consisting of all those f ∈ L⁰(X) for which the scalar function ${| | f (\cdot) | |}_{X}$ belongs to E. Let E(X)˜ stand for the order dual of E(X). For u ∈ E⁺ let $D_{u} (= {f \in E (X) : | | f (\cdot) | |}_{X} \leq u)$ stand for the order interval in E(X). For a real Banach space $(Y, | | \cdot | |_{Y})$ a linear operator T: E(X) → Y is said to be order-bounded whenever for each u ∈ E⁺ the set...

Orlicz bounds for operators of restricted weak type

Paul Alton Hagelstein (2005)

Colloquium Mathematicae

It is shown that if T is a sublinear translation invariant operator of restricted weak type (1,1) acting on L¹(𝕋), then T maps simple functions in L log L(𝕋) boundedly into L¹(𝕋).

Orlicz spaces for which the Hardy-Littlewood maximal operators is bounded.

Diego Gallardo (1988)

Publicacions Matemàtiques

Let M be the Hardy-Littlewood maximal operator defined by:Mf(x) = supx ∈ Q 1/|Q| ∫Q |f| dx, (f ∈ Lloc(Rn)),where the supreme is taken over all cubes Q containing x and |Q| is the Lebesgue measure of Q. In this paper we characterize the Orlicz spaces Lφ*, associated to N-functions φ, such that M is bounded in Lφ*. We prove that this boundedness is equivalent to the complementary N-function ψ of φ satisfying the Δ2-condition in [0,∞), that is, sups>0 ψ(2s) / ψ(s) < ∞.

Paracommutators. Brief introduction, open problems.

Jaak Peetre (1989)

Revista Matemática de la Universidad Complutense de Madrid

We review the basic facts about the theory of paracommutators in Rn (sec S. Janson, J. Peetre, Trans. Am. Math. Soc. 305 (1988), 467504). We also give an interpretation of paracommutators from the point of view of group representations. This suggests a generalization to more general groups. Here we sketch a theory of paracommutators over stratified groups. This include the famous Heisenberg group. Finally, we take up the question of generalizing the notion of Schatten-von Neumann trace ideals to...

Partial differential equations in Banach spaces involving nilpotent linear operators

Antonia Chinnì, Paolo Cubiotti (1996)

Annales Polonici Mathematici

Let E be a Banach space. We consider a Cauchy problem of the type ⎧ $D_{t}^{k} u + \sum_{j = 0}^{k - 1} \sum_{| α | \leq m} A_{j, α} (D_{t}^{j} D_{x}^{α} u) = f$ in $ℝ^{n + 1}$ , ⎨ ⎩ $D_{t}^{j} u (0, x) = φ_{j} (x)$ in $ℝ^{n}$ , j=0,...,k-1, where each $A_{j, α}$ is a given continuous linear operator from E into itself. We prove that if the operators $A_{j, α}$ are nilpotent and pairwise commuting, then the problem is well-posed in the space of all functions $u \in C^{\infty} (ℝ^{n + 1}, E)$ whose derivatives are equi-bounded on each bounded subset of $ℝ^{n + 1}$ .

Partial integral operators in Orlicz spaces with mixed norm

J. Appell, A. Kalitvin, P. Zabreĭko (1998)

Colloquium Mathematicae

Perron root of a convex combination of a positive kernel and its adjoint

Ivo Marek (1978)

Acta Universitatis Carolinae. Mathematica et Physica

Podal subspaces on the unit polydisk

Kunyu Guo (2002)

Studia Mathematica

Beurling's classical theorem gives a complete characterization of all invariant subspaces in the Hardy space H²(D). To generalize the theorem to higher dimensions, one is naturally led to determining the structure of each unitary equivalence (resp. similarity) class. This, in turn, requires finding podal (resp. s-podal) points in unitary (resp. similarity) orbits. In this note, we find that H-outer (resp. G-outer) functions play an important role in finding podal (resp. s-podal) points. By the methods...

Point interactions in Lp .

W. Gaspers, P. Clément (1993)

Semigroup forum

Points fixes et théorèmes ergodiques dans les espaces L¹(E)

Mourad Besbes (1992)

Studia Mathematica

We prove that for each linear contraction T : X → X (∥T∥ ≤ 1), the subspace F = {x ∈ X : Tx = x} of fixed points is 1-complemented, where X is a suitable subspace of L¹(E*) and E* is a separable dual space such that the weak and weak* topologies coincide on the unit sphere. We also prove some related fixed point results.

Pointwise limit theorem for a class of unbounded operators in $^{r}$ -spaces

Ryszard Jajte (2007)

Studia Mathematica

We distinguish a class of unbounded operators in $^{r}$ , r ≥ 1, related to the self-adjoint operators in ². For these operators we prove a kind of individual ergodic theorem, replacing the classical Cesàro averages by Borel summability. The result is equivalent to a version of Gaposhkin’s criterion for the a.e. convergence of operators. In the proof, the theory of martingales and interpolation in $^{r}$ -spaces are applied.

Pointwise multiplication operators on weighted Banach spaces of analytic functions

J. Bonet, P. Domański, M. Lindström (1999)

Studia Mathematica

For a wide class of weights we find the approximative point spectrum and the essential spectrum of the pointwise multiplication operator $M_{φ}$ , $M_{φ} (f) = φ f$ , on the weighted Banach spaces of analytic functions on the disc with the sup-norm. Thus we characterize when $M_{φ}^{'}$ is Fredholm or is an into isomorphism. We also study cyclic phenomena for the adjoint map $M_{φ}^{'}$ .

Pointwise multipliers from weighted Bergman spaces and Hardy spaces to weighted Bergman spaces.

Zhao, Ruhan (2004)

Annales Academiae Scientiarum Fennicae. Mathematica

Pointwise multipliers on martingale Campanato spaces

Eiichi Nakai, Gaku Sadasue (2014)

Studia Mathematica

We introduce generalized Campanato spaces $_{p, ϕ}$ on a probability space (Ω,ℱ,P), where p ∈ [1,∞) and ϕ: (0,1] → (0,∞). If p = 1 and ϕ ≡ 1, then $_{p, ϕ} = B M O$ . We give a characterization of the set of all pointwise multipliers on $_{p, ϕ}$ .

Positivity in the theory of supercyclic operators

F. León-Saavedra, A. Piqueras-Lerena (2007)

Banach Center Publications

A bounded linear operator T defined on a Banach space X is said to be supercyclic if there exists a vector x ∈ X such that the projective orbit {λTⁿx : λ ∈ ℂ, n ∈ ℕ} is dense in X. The aim of this survey is to show the relationship between positivity and supercyclicity. This relationship comes from the so called Positive Supercyclicity Theorem. Throughout this exposition, interesting new directions and open problems will appear.

Currently displaying 381 – 400 of 659

Previous Page 20 Next

Displaying 381 – 400 of 659

Order properties of the space of finitely additive transition functions.

Order properties of the space of strongly additive transition functions.

Order-bounded operators from vector-valued function spaces to Banach spaces

Orlicz bounds for operators of restricted weak type

Orlicz spaces for which the Hardy-Littlewood maximal operators is bounded.

Paracommutators. Brief introduction, open problems.

Partial differential equations in Banach spaces involving nilpotent linear operators

Partial integral operators in Orlicz spaces with mixed norm

Perron root of a convex combination of a positive kernel and its adjoint

Podal subspaces on the unit polydisk

Point interactions in Lp .

Points fixes et théorèmes ergodiques dans les espaces L¹(E)

Pointwise limit theorem for a class of unbounded operators in $^{r}$ -spaces

Pointwise multiplication operators on weighted Banach spaces of analytic functions

Pointwise multipliers from weighted Bergman spaces and Hardy spaces to weighted Bergman spaces.

Pointwise multipliers on martingale Campanato spaces

Positivity in the theory of supercyclic operators

Potential operators in variable exponent Lebesgue spaces: two-weight estimates.

p-representable operators in Banach spaces.

Products of composition and differentiation operators from $𝒬_{K} (p, q)$ spaces to Bloch-type spaces.

Currently displaying 381 – 400 of 659