A tight upper bound on the (2,1)-total labeling number of outerplanar graphs

Toru Hasunuma, Toshimasa Ishii, Hirotaka Ono +1

A $(2,1)$-total labeling of a graph $G$ is an assignment $f$ from the vertex set $V(G)$ and the edge set $E(G)$ to the set $\{0,1,...,k\}$ of nonnegative integers such that $|f(x)-…