on label graphoidal covering number-i
نویسندگان
چکیده
let $g=(v, e)$ be a graph with $p$ vertices and $q$ edges. an emph{acyclic graphoidal cover} of $g$ is a collection $psi$ of paths in $g$ which are internally-disjoint and cover each edge of the graph exactly once. let $f: vrightarrow {1, 2, ldots, p}$ be a bijective labeling of the vertices of $g$. let $uparrow!g_f$ be the directed graph obtained by orienting the edges $uv$ of $g$ from $u$ to $v$ provided $f(u)< f(v)$. if the set $psi_f$ of all maximal directed paths in $uparrow!g_f$, with directions ignored, is an acyclic graphoidal cover of $g$, then $f$ is called a emph{graphoidal labeling} of $g$ and $g$ is called a emph{label graphoidal graph} and $eta_l=min{|psi_f|: f {rm is a graphoidal labeling of} g}$ is called the emph{label graphoidal covering number} of $g$. in this paper we characterize graphs for which (i) $eta_l=q-m$, where $m$ is the number of vertices of degree 2 and (ii) $eta_l= q$. also, we determine the value of label graphoidal covering number for unicyclic graphs.
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عنوان ژورنال:
transactions on combinatoricsناشر: university of isfahan
ISSN 2251-8657
دوره 1
شماره 4 2012
میزبانی شده توسط پلتفرم ابری doprax.com
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