In this paper we introduce approximate duality of g-frames in Hilbert $C^\ast$-modules and we show that approximate duals of g-frames in Hilbert $C^\ast$-modules share many useful properties with those in Hilbert spaces. Moreover, we obtain some new results for approximate duality of frames and g-frames in Hilbert spaces; in particular, we consider approximate duals of $\varepsilon$-nearly Parseval and $\varepsilon$-close frames.
AZANDARYANI, MORTEZA MIRZAEE
"Approximate duals and nearly Parseval frames,"
Turkish Journal of Mathematics: Vol. 39:
4, Article 7.
Available at: https://journals.tubitak.gov.tr/math/vol39/iss4/7