G-frames and their duals for Hilbert C*-modules

Certain facts about frames and generalized frames (g- frames) are extended for the g-frames for Hilbert C*-modules. It is shown that g-frames for Hilbert C*-modules share several useful properties with those for Hilbert spaces. The paper also character- izes the operators which preserve the class of g-frames for Hilbert C*-modules. Moreover, a necessary and suffcient condition is ob- tained for an operator T whose corresponding singleton set {T} to be a g-frame. Finally, some characterizations of dual g-frames for Hilbert spaces and Hilbert C*-modules are given.