Comments on “A Hierarchy of Importance Indices”

The paper by Hwang (IEEE Trans. Reliability, vol. 54, pp. 169–172, 2005) presented structural importance measures in terms of cutsets or pathsets, and investigated how they are related. Hwang's paper has made contributions to importance measures. However, several errors which cause confusions are found in the paper. This note is to clarify these errors, and discuss the suspicions.