Cojuhari, P.Gheondea, Aurelian2021-03-042021-03-0420201454-9069http://hdl.handle.net/11693/75788We compare the concept of triplet of closely embedded Hilbert spaces with that of generalised triplet of Hilbert spaces in the sense of Berezanskii by showing when they coincide, when they are different, and when starting from one of them one can naturally produce the other one that essentially or fully coincides.EnglishGeneralised triplet of Hilbert spacesClosed embeddingTriplet of closely embedded Hilbert spacesRigged Hilbert spacesArticle