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Identifying Codes on Directed De Bruijn Graphs. (arXiv:1412.5842v3 [math.CO] UPDATED)
来源于:arXiv
For a directed graph $G$, a $t$-identifying code is a subset $S\subseteq
V(G)$ with the property that for each vertex $v\in V(G)$ the set of vertices of
$S$ reachable from $v$ by a directed path of length at most $t$ is both
non-empty and unique. A graph is called {\it $t$-identifiable} if there exists
a $t$-identifying code. This paper shows that the de~Bruijn graph
$\vec{\mathcal{B}}(d,n)$ is $t$-identifiable if and only if $n \geq 2t-1$. It
is also shown that a $t$-identifying code for $t$-identifiable de~Bruijn graphs
must contain at least $d^{n-1}(d-1)$ vertices, and constructions are given to
show that this lower bound is achievable $n \geq 2t$. Further a (possibly)
non-optimal construction is given when $n=2t-1$. Additionally, with respect to
$\vec{\mathcal{B}}(d,n)$ we provide upper and lower bounds on the size of a
minimum \textit{$t$-dominating set} (a subset with the property that every
vertex is at distance at most $t$ from the subset), that the minimum size of a
\textit{di 查看全文>>