Approximate Duals of g-frames and Fusion Frames in Hilbert C*-modules

In this paper, we study approximate duals of g-frames and fusion frames in Hilbert C*-modules. We get some relations between approximate duals of g-frames and biorthogonal Bessel sequences, and using these relations, some results for approximate duals of modular Riesz bases and fusion frames are obtained. Moreover, we generalize the concept of Q-approximate duality of g-frames and fusion frames to Hilbert C*-modules, where Q is an adjointable operator, and obtain some properties of this kind of approximate duals.