A new class of lower bounds to information rates of stationary sources via conditional rate-distortion functions

A new class of lower bounds to rate-distortion functions of stationary processes with memory and single-letter vector-valued distortion measures is derived. This class is shown to include or imply all other well-known lower bounds to rates of such sources and distortion measures. The derivation is based on the definition and properties of the conditional rate-distortion function. In addition to providing a unified and intuitive approach to lower bounds, this approach yields several interesting relations among conditional, joint, and marginal rates that are similar to and sometimes identical with the analogous relations among the corresponding entropies.