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Multiplicative functionals on algebras of differentiable functions.

Jesús A. Jaramillo (1990)

Extracta Mathematicae

Let Ω be an open subset of a real Banach space E and, for 1 ≤ m ≤, let Cm(Ω) denote the algebra of all m-times continuously Fréchet differentiable real functions defined on Ω. We are concerned here with the question as to wether every nonzero algebra homomorphism φ: Cm(Ω) → R is given by evaluation at some point of Ω, i.e., if there exists some a ∈ Ω such that φ(f) = f(a) for each f ∈ Cm(Ω). This problem has been considered in [1,4,5] and [6]. In [6], a positive answer is given in the case that...

Multiplicative structure of de Branges's spaces.

Benjamin A. Lotto, Donald Sarason (1991)

Revista Matemática Iberoamericana

L. de Branges has originated a viewpoint one of whose repercussions has been the detailed analysis of certain Hilbert spaces of holomorphic functions contained within the Hardy space H2 of the unit disk (...).

Multiplier transformations on H p spaces

Daning Chen, Dashan Fan (1998)

Studia Mathematica

The authors obtain some multiplier theorems on H p spaces analogous to the classical L p multiplier theorems of de Leeuw. The main result is that a multiplier operator ( T f ) ( x ) = λ ( x ) f ̂ ( x ) ( λ ∈ C ( ...

Multipliers and hereditary subalgebras of operator algebras

Damon M. Hay (2011)

Studia Mathematica

We generalize some technical results of Glicksberg to the realm of general operator algebras and use them to give a characterization of open and closed projections in terms of certain multiplier algebras. This generalizes a theorem of J. Wells characterizing an important class of ideals in uniform algebras. The difficult implication in our main theorem is that if a projection is open in an operator algebra, then the multiplier algebra of the associated hereditary subalgebra arises as the closure...

Multipliers of de Branges-Rovnyak spaces in H2.

Fernando Daniel Suárez (1995)

Revista Matemática Iberoamericana

In 1966 de Branges and Rovnyak introduced a concept of complementation associated to a contraction between Hilbert spaces that generalizes the classical concept of orthogonal complement. When applied to Toeplitz operators on the Hardy space of the disc, H2, this notion turned out to be the starting point of a beautiful subject, with many applications to function theory. The work has been in constant progress for the last few years. We study here the multipliers of some de Branges-Rovnyak spaces...

Murphy's "Positive definite kernels and Hilbert C*-modules" reorganized

Franciszek Hugon Szafraniec (2010)

Banach Center Publications

The paper the title refers to is that in Proceedings of the Edinburgh Mathematical Society, 40 (1997), 367-374. Taking it as an excuse we intend to realize a twofold purpose: 1° to atomize that important result showing by the way connections which are out of favour, 2° to rectify a tiny piece of history. The objective 1° is going to be achieved by adopting means adequate to goals; it is of great gravity and this is just Mathematics. The other, 2°, comes...

Musielak-Orlicz spaces and prediction problems

Kazimierz Urbanik (2004)

Banach Center Publications

By a harmonizable sequence of random variables we mean the sequence of Fourier coefficients of a random measure M: X ₙ ( M ) = ∫ 0 1 e 2 π n i s M ( d s ) (n = 0,±1,...) The paper deals with prediction problems for sequences Xₙ(M) for isotropic and atomless random measures M. The crucial result asserts that the space of all complex-valued M-integrable functions on the unit interval is a Musielak-Orlicz space. Hence it follows that the problem for Xₙ(M) (n = 0,±1,...) to be deterministic is in fact an extremal problem of Szegö’s type...

Musielak-Orlicz-Hardy Spaces Associated with Operators Satisfying Reinforced Off-Diagonal Estimates

The Anh Bui, Jun Cao, Luong Dang Ky, Dachun Yang, Sibei Yang (2013)

Analysis and Geometry in Metric Spaces

Let X be a metric space with doubling measure and L a one-to-one operator of type ω having a bounded H∞ -functional calculus in L2(X) satisfying the reinforced (pL; qL) off-diagonal estimates on balls, where pL ∊ [1; 2) and qL ∊ (2;∞]. Let φ : X × [0;∞) → [0;∞) be a function such that φ (x;·) is an Orlicz function, φ(·;t) ∊ A∞(X) (the class of uniformly Muckenhoupt weights), its uniformly critical upper type index l(φ) ∊ (0;1] and φ(·; t) satisfies the uniformly reverse Hölder inequality of order...

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