“…The induced subgraph of G T on T x is a discrete graph, i.e., a graph without any edge, while for distinct vertices x, y of G, each vertex of T x is adjacent to all vertices of T y in G T if and only if x is adjacent to y in G, see [8,16,17] for details. The previous work shows that graph blow-up plays an essential role in the theory of the co-maximal ideal graph of a ring, see [21,22] for the concise definitions, the history, the recent development, and a list of references. This paper is organized in the following way.…”