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Maximum Size of a Minimum Watching System and the Graphs Achieving the Bound

David Auger 1 Irène Charon 2 Olivier Hudry 2 Antoine Lobstein 2, 3
LTCI - Laboratoire Traitement et Communication de l'Information, Télécom ParisTech
Abstract : Let G = (V(G);E(G)) be an undirected graph. A watcher w of G is a couple w = (l(w), A(w)), where l(w) belongs to V(G) and A(w) is a set of vertices of G at distance 0 or 1 from l(w). If a vertex v belongs to A(w), we say that v is covered by w. Two vertices v1 and v2 in G are said to be separated by a set of watchers if the list of the watchers covering v1 is diff erent from that of v2. We say that a set W of watchers is a watching system for G if every vertex v is covered by at least one watcher w belonging to W, and every two vertices v1, v2 are separated by W. The minimum number of watchers necessary to watch G is denoted by w(G). We give an upper bound on w(G) for connected graphs of order n and characterize the trees attaining this bound, before studying the more complicated characterization of the connected graphs attaining this bound.
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Submitted on : Monday, March 19, 2012 - 9:39:43 PM
Last modification on : Monday, January 24, 2022 - 11:43:20 AM
Long-term archiving on: : Wednesday, June 20, 2012 - 2:35:09 AM


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  • HAL Id : hal-00680690, version 1


David Auger, Irène Charon, Olivier Hudry, Antoine Lobstein. Maximum Size of a Minimum Watching System and the Graphs Achieving the Bound. 2012. ⟨hal-00680690⟩



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