Comments on 'On Integral Graphs Which Belong to the Class (alpha K-a,K-b)over-bar)over bar>'' [Graphs Comb. 19, 527-532 (2003)]

摘要

Lepovic ' gave a characterization of integral graphs of the form aKa; b in ``On Integral Graphs Which Belong to the Class aKa;b'' [Graphs Comb. 19, 527-532 (2003)]. However, for majority of the graphs aKa; b declared to be integral in this result, their spectrum also includes non-integer eigenvalues 1 ffiffiffiffiffi abp. Here we correct this result and indicate that integral graphs of this form are indeed very rare.