Comments on "Heuristic search for scheduling flexible manufacturing systems using lower bound reachability matrix"

Four new heuristic functions of A^* algorithm are proposed in the above paper. The authors claim that these functions are more efficient in terms of the search space and computation time than that of using resource cost reachability (RCR) matrix. However, it is not always true for one of the proposed functions, h"L"B"R(M). This comment gives some counter examples to demonstrate it.