The (k − 1)-fault diameter Dk(G) of a k-connected graph G is the maximum diameter of G− F for any F ⊂ V (G) with |F | < k. Krishnamoorthy and Krishnamurthy first proposed this concept and gave Dκ(G1)+κ(G2)(G1 ×G2) Dκ(G1)(G1)+ Dκ(G2)(G2) when κ(G1 ×G2)= κ(G1)+ κ(G2), where κ(G) is the connectivity of G. This paper gives a counterexample to this bound and establishes Dk1+k2(G1 × G2) Dk1(G1) +Dk2 ...
