On spectral pictures
نویسنده
چکیده
The “spectral picture” of a bounded operator on a Banach space consists of its essential spectrum together with a mapping from its holes to the group of integers, obtained by taking the Fredholm index. In this note we abstract this from the Calkin algebra to a general Banach algebra, replacing the integers with the quotient of the group of invertibles by its connected component of the identity.
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