The minimax distortion redundancy in noisy source coding

The authors consider a source emitting the sequence of pairs {(X_k,Z_k)}_k≥l, which are independent drawings of dependent random variables (X, Z), taking values in X×Z and distributed according to P_x,z. The problem of noisy coding is that of representing the sequence {X_k}_k≥l by the sequence {Y_k}_k≥l (of alphabet Y) with lowest possible distortion (measured by a given distortion measure ρ), based on observing {Z_k}_k≥l, while operating at a given information rate. The authors´ goal in this work is to answer the immediate questions that arise for the case where P_x,z, rather than being completely specified, is only known to belong to a given set Λ.