🌐EnglishEnglishDeutschEspañolFrançaisPolski中文日本語EntityQ904849· pop 6· linked from 24 articlesPartial isometrylinear map between Hilbert spacesAvailable in 6 languagesFrançaisDeutsch中文日本語Polskivia Wikidata sitelinks · CC0ConnectionsInternational Standard Book NumberEntitycomplex numberEntityCategoriesC*-algebrasOperator theorySemigroup theory