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Keywords:
integral sum graph; saturated vertex; edge-chromatic number
Summary:
As introduced by F. Harary in 1994, a graph $G$ is said to be an $integral$ $sum$ $graph$ if its vertices can be given a labeling $f$ with distinct integers so that for any two distinct vertices $u$ and $v$ of $G$, $uv$ is an edge of $G$ if and only if $f(u)+f(v)=f(w)$ for some vertex $w$ in $G$. \endgraf We prove that every integral sum graph with a saturated vertex, except the complete graph $K_3$, has edge-chromatic number equal to its maximum degree. (A vertex of a graph $G$ is said to be {\it saturated} if it is adjacent to every other vertex of $G$.) Some direct corollaries are also presented.
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