Título inglés |
Linear maps preserving the generalized spectrum. |
Título español |
Aplicaciones lineales que conservan el espectro generalizado. |
Autor/es |
Mbekhta, Mostafa |
Organización |
UFR Math. Univ. Lille I, Villeneuve d'Ascq, Francia |
Revista |
0213-8743 |
Publicación |
2007, 22 (1): 45-54, 27 Ref. |
Tipo de documento |
articulo |
Idioma |
Inglés |
Resumen inglés |
Let H be an infinite-dimensional separable complex Hilbert space and B(H) the algebra of all bounded linear operators on H. For an operator T in B(H), let σg(T) denote
the generalized spectrum of T. In this paper, we prove that if φ: B(H) → B(H) is a surjective linear map, then φ preserves the generalized spectrum (i.e. σg(φ(T)) = σg(T)
for every T Î B(H)) if and only if there is A Î B(H) invertible such that either φ(T) =
ATA-1 for every T Î B(H), or φ(T) = ATtrA-1 for every T Î B(H). Also, we prove that γ(φ(T)) = γ(T) for every T Î B(H) if and only if there is U Î B(H) unitary such that either φ(T) = UTU* for every T Î B(H) or φ(T) = UTtrU* for every T Î B(H). Here γ(T) is the reduced minimum modulus of T. |
Acceso al artículo completo |