摘要：We give new characterizations of Riesz-type frames, on equivalent
conditions for a continuous frame to be a Riesz-type frame and on equivalency
relations between Riesz-type frames and continuous frames. We characterize also the
Riesz-type frames by using a bounded linear operator . Finally, we study the stability of
alternate duals of continuous frames and we prove that if two continuous frames are close
to each other, then we can find alternate duals of them which are close to each other.
