Resumen de Group Riesz and frame sequences: the Bracket and the Gramian
Davide Barbieri, Eugenio Hernández Rodríguez 
, Victoria Paternostro
Given a discrete group and a unitary representation on a Hilbert space , we prove that the notions of operator Bracket map and Gramian coincide on a dense set of . As a consequence, combining this result with known frame theory, we can recover all previous Bracket characterizations of Riesz and frame sequences generated by a single element under a unitary representation.
