3 papers
math.OA2013
On Isometric Representations of the Perforated Semigroup
Suren A. Grigoryan, Vardan H. Tepoyan
We study isometric representations of the semigroup . Notion of an inverse representation is introduced and a complete description (up to unitary equi…
math.OA2013
On -extensions of the semigroup
T. A. Grigoryan, E. V. Lipacheva, V. H. Tepoyan
We study inverse -extensions of the semigroup . It is shown that -extension of the semigroup is inverse, iff its -extension coincides with $π(…
math.OA2013
On The Extension of the Toeplitz Algebra by Isometries
T. A. Grigoryan, E. V. Lipacheva, V. H. Tepoyan
We introduce the notion of π-extension of the semigroup \mathbb{Z}_+ and study the extensions of the Toeplitz algebras by isometric operators. We show that when the action of the T…