Displaying similar documents to “Operators of Hankel type”

On Pták’s generalization of Hankel operators

Carmen H. Mancera, Pedro José Paúl (2001)

Czechoslovak Mathematical Journal

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In 1997 Pták defined generalized Hankel operators as follows: Given two contractions T 1 ∈ ℬ ( ℋ 1 ) and T 2 ∈ ℬ ( ℋ 2 ) , an operator X ℋ 1 → ℋ 2 is said to be a generalized Hankel operator if T 2 X = X T 1 * and X satisfies a boundedness condition that depends on the unitary parts of the minimal isometric dilations of T 1 and T 2 . This approach, call it (P), contrasts with a previous one developed by Pták and Vrbová in 1988, call it (PV), based on the existence of a previously defined generalized Toeplitz operator. There seemed to be a strong...

On truncations of Hankel and Toeplitz operators.

Aline Bonami, Joaquim Bruna (1999)

Publicacions Matemàtiques

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We study the boundedness properties of truncation operators acting on bounded Hankel (or Toeplitz) infinite matrices. A relation with the Lacey-Thiele theorem on the bilinear Hilbert transform is established. We also study the behaviour of the truncation operators when restricted to Hankel matrices in the Schatten classes.

Two-parametric liftings of Toeplitz forms.

Pedro Alegría Ezquerra (1992)

Extracta Mathematicae

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The parametrization problem of the minimal unitary extensions of an isometric operator allows its application, through the spectral theorem, to the case of the Fourier representations of a bounded Hankel form with respect to the norms (∫ |f|dμ) and (∫ |f|dμ) where μ, μ are positive finite measures in T~[0,2π[ (see [1]). In this work we develop a similar procedure for the two-parametric case, where μ, μ are positive measures defined in T~[0,2π[x[0,2π[. With this purpose, we define the...