Neighbor sum distinguishing total coloring of IC-planar graphs (Q2185920)

The authors consider the problem of neighbor sum distinguishing total coloring of IC-planar graphs. A proper total-\(k\)-coloring of a graph \(G\) is a mapping \(c: V(G)\cup E(G) \rightarrow \{1, 2, \ldots, k\}\) such that any two adjacent elements in \(V(G) \cup E(G)\) receive different colors. Let \(\sum_c(u)\) denote the sum of the color of a vertex \(v\) and the colors of all edges incident with \(v\). If for each edge \(uv \in E(G)\), \(\sum_c(u) \ne\sum_c (v)\), then such a proper total-\(k\)-coloring is called a \(k\)-neighbor sum distinguishing total coloring, denoted by tnsd-\(k\)-coloring, for short. The least number \(k\) needed for such a coloring of \(G\), denoted by \(\chi^{\prime\prime}_{\Sigma}(G)\), is the neighbor sum distinguishing total chromatic number. The problem is very well known in the literature. There is a known conjecture, posed by \textit{M. Pilśniak} and \textit{M. Woźniak} [Graphs Comb. 31, No. 3, 771--782 (2015; Zbl 1312.05054)], that \(\chi^{\prime\prime}_{\Sigma}(G)\leq \Delta(G)+3\) for any graph \(G\). Also some other bounds on \(\chi^{\prime\prime}_{\Sigma}(G)\)are known proved for general or particular classes of graphs. This paper contributes a lot to the knowledge in the area of neighbor sum distinguishing total coloring by proving that \(\chi^{\prime\prime}_{\Sigma}(G)\leq \Delta(G)+2\) for IC-planar graphs without 2-vertex incident with crossed edge and with \(\Delta(G)\geq 14\). The proof of the result is very interesting and carried with great care. I find the paper very valuable.