Revision as of 15:49, 9 April 2023 by imported>Equinox(Created page with "==English== {{wp}} ===Noun=== {{en-noun}} # {{lb|en|math}} In operator theory, a set <math>X\subseteq\mathbb{C}</math> such that, for a (possibly unbounded) linear operator <math>T</math> on a Banach space, the spectrum of <math>T</math> is in <math>X</math> and von Neumann's inequality holds for <math>T</math> on <math>X</math>.")