Título inglés |
Two-parametric liftings of Toeplitz forms. |
Título español |
Levantamientos biparamétricos de formas de Toeplitz. |
Autor/es |
Alegría Ezquerra, Pedro |
Organización |
Dep. Mat. Univ. País Vasco E.H.U., Bilbao, España |
Revista |
0213-8743 |
Publicación |
1992, 7 (1): 16-19, 4 Ref. |
Tipo de documento |
articulo |
Idioma |
Inglés |
Resumen inglés |
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|2dμ1)1/2 and (∫ |f|2dμ2)1/2 where μ1, μ2 are positive finite measures in T~[0,2π[ (see [1]). In this work we develop a similar procedure for the two-parametric case, where μ1, μ2 are positive measures defined in T2~[0,2π[x[0,2π[. With this purpose, we define the generalized Toeplitz forms on the space of the two-variable trigonometric polynomials and use the lifting existence theorems due to Cotlar and Sadosky [3]. We provide a parametrization formula which is also valid to the special case of the Nehari problem. |
Clasificación UNESCO |
120201 |
Palabras clave español |
Formas de Toeplitz ; Operadores isométricos ; Extensión ; Parametrización ; Polinomios trigonométricos |
Código MathReviews |
MR1203434 |
Acceso al artículo completo |