2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/134573We study the problem of computing the rate-distortion function for sources with feed-forward and the capacity for channels with feedback. The formulas (involving directed information) for the optimal rate-distortion function with feed-forward and channel capacity with feedback are multi-letter expressions and cannot be computed easily in general. In this work, we derive conditions under which these can be computed for a large class of sources/channels with memory and distortion/cost measures. Illustrative examples are also provided.5 pages, Submitted to ISIT 2007. Corrected typos, latest version that appeared in ISIT 2007Information Theorytext