g-frames and their duals for hilbert c*-modules

abstract. 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.