A graph \(G\) is called an \(M_r(k)\)-graph if \(G\) has no \(k\)-list assignment to its vertices with exactly \(r\) vertex colorings. We characterize all \(M_3(2)\)-graphs. More precisely, it is shown that a connected graph \(G\) is an \(M_3(2)\)-graph if and only if each block of \(G\) is a complete graph with at least three vertices.
1970-2025 CP (Manitoba, Canada) unless otherwise stated.