Displaying similar documents to “On continuity of linear transformations commuting with generalized scalar operators in Banach space”

Commutativity of compact selfadjoint operators

G. Greiner, W. Ricker (1995)

Studia Mathematica

Similarity:

The relationship between the joint spectrum γ(A) of an n-tuple A = ( A 1 , . . . , A n ) of selfadjoint operators and the support of the corresponding Weyl calculus T(A) : f ↦ f(A) is discussed. It is shown that one always has γ(A) ⊂ supp (T(A)). Moreover, when the operators are compact, equality occurs if and only if the operators A j mutually commute. In the non-commuting case the equality fails badly: While γ(A) is countable, supp(T(A)) has to be an uncountable set. An example is given showing that, for non-compact...