About Deenitions of Pseudospectra of Closed Operators in Banach Spaces
نویسندگان
چکیده
Our goal, in this paper, is to study some equivalent deenitions of the pseudospectra of a closed linear operator. We start from two deenitions, one with strict inequality and the other with non-strict inequality. The rst deenition makes the pseudospectrum open and the second makes it closed. We will show the subtle diierence between these seemingly almost identical deenitions and the relations between them.
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