Spectral factorization of measurable rectangular matrix functions and the vector-valued Riemann problem

Autores: I. M. Spitkovsky, M. Rakowsky
Localización: Revista matemática iberoamericana, ISSN 0213-2230, Vol. 12, Nº 3, 1996, págs. 669-696
Idioma: inglés
DOI: 10.4171/rmi/211
Títulos paralelos:
- Factorización espectral de funciones matriciales rectangulares medibles y el problema de Riemann valuado con vectores.
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Resumen
- We define spectral factorization in Lp (or a generalized Wiener-Hopf factorization) of a measurable singular matrix function on a simple closed rectifiable contour G. Such factorization has the same uniqueness properties as in the nonsingular case. We discuss basic properties of the vector valued Riemann problem whose coefficient takes singular values almost everywhere on G. In particular, we introduce defect numbers for this problem which agree with the usual defect numbers in the case of a nonsingular coefficient. Based on the Riemann problem, we obtain a necessary and sufficient condition for existence of a spectral factorization in Lp.