Displaying similar documents to “Cartesian subdirect irreducibility in graphs”

Star Coloring of Subcubic Graphs

T. Karthick, C.R. Subramanian (2013)

Discussiones Mathematicae Graph Theory

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A star coloring of an undirected graph G is a coloring of the vertices of G such that (i) no two adjacent vertices receive the same color, and (ii) no path on 4 vertices is bi-colored. The star chromatic number of G, χs(G), is the minimum number of colors needed to star color G. In this paper, we show that if a graph G is either non-regular subcubic or cubic with girth at least 6, then χs(G) ≤ 6, and the bound can be realized in linear time.

Spatially-distributed coverage optimization and control with limited-range interactions

Jorge Cortés, Sonia Martínez, Francesco Bullo (2005)

ESAIM: Control, Optimisation and Calculus of Variations

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This paper presents coordination algorithms for groups of mobile agents performing deployment and coverage tasks. As an important modeling constraint, we assume that each mobile agent has a limited sensing or communication radius. Based on the geometry of Voronoi partitions and proximity graphs, we analyze a class of aggregate objective functions and propose coverage algorithms in continuous and discrete time. These algorithms have convergence guarantees and are spatially distributed...

On potentially H -graphic sequences

Meng Xiao Yin, Jian Hua Yin (2007)

Czechoslovak Mathematical Journal

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For given a graph H , a graphic sequence π = ( d 1 , d 2 , ... , d n ) is said to be potentially H -graphic if there is a realization of π containing H as a subgraph. In this paper, we characterize the potentially ( K 5 - e ) -positive graphic sequences and give two simple necessary and sufficient conditions for a positive graphic sequence π to be potentially K 5 -graphic, where K r is a complete graph on r vertices and K r - e is a graph obtained from K r by deleting one edge. Moreover, we also give a simple necessary and sufficient condition...