TBSs in some minimum coverings

Abstract: Let be a -covering with excess and a blocking set . Let , , , be all connected components of with at least two vertices (note that if ). The blocking set is called tight if further and for . In this paper, we give a complete solution for the existence of a minimum -covering admitting a blocking set (BS), or a tight blocking set (TBS) for any and when and . [Copyright &y& Elsevier]