On hierarchical type covering
This correspondence focuses on a significant distinction between two hierarchical type covering strategies, namely, weak and strong covering, and on the impact of this distinction on known results. In particular, it is demonstrated that the rate region for weak covering, whose natural use is in scalable source coding, is generally larger than the rate region for strong covering, which is primarily useful in hierarchical guessing. This correspondence also presents a corrected converse result for the hierarchical guessing problem.