Approximate duals and nearly Parseval frames

In this paper we introduce approximate duality of g-frames in Hilbert C*-modules and we show that approximate duals of g-frames in Hilbert C*-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 epsilon-nearly Parseval and epsilon-close frames.