Volume 12, Issue 1 Sebastian Geethika Daniel Sukumar On the open ball centered at an invertible element of a Banach algebra Downloads Abstract PDF Full article PDF DOI { copied = true; setTimeout(() => copied = false, 2000) })" :aria-label="copied ? 'DOI copied' : 'Copy DOI'" :title="copied ? 'Copied' : 'Copy DOI'" > Find all available articles from these authors Sebastian Geethika Daniel Sukumar Find more articles with the same keywords invertible elements spectrum norm attaining semi simple Find more articles with the same subject classes 46H05 46H20