25 research outputs found
The Generalized Distance Spectrum of the Join of Graphs
Let G be a simple connected graph. In this paper, we study the spectral properties of the generalized distance matrix of graphs, the convex combination of the symmetric distance matrix D(G) and diagonal matrix of the vertex transmissions Tr(G) . We determine the spectrum of the join of two graphs and of the join of a regular graph with another graph, which is the union of two different regular graphs. Moreover, thanks to the symmetry of the matrices involved, we study the generalized distance spectrum of the graphs obtained by generalization of the join graph operation through their eigenvalues of adjacency matrices and some auxiliary matrices
Coloring, location and domination of corona graphs
A vertex coloring of a graph is an assignment of colors to the vertices
of such that every two adjacent vertices of have different colors. A
coloring related property of a graphs is also an assignment of colors or labels
to the vertices of a graph, in which the process of labeling is done according
to an extra condition. A set of vertices of a graph is a dominating set
in if every vertex outside of is adjacent to at least one vertex
belonging to . A domination parameter of is related to those structures
of a graph satisfying some domination property together with other conditions
on the vertices of . In this article we study several mathematical
properties related to coloring, domination and location of corona graphs.
We investigate the distance- colorings of corona graphs. Particularly, we
obtain tight bounds for the distance-2 chromatic number and distance-3
chromatic number of corona graphs, throughout some relationships between the
distance- chromatic number of corona graphs and the distance- chromatic
number of its factors. Moreover, we give the exact value of the distance-
chromatic number of the corona of a path and an arbitrary graph. On the other
hand, we obtain bounds for the Roman dominating number and the
locating-domination number of corona graphs. We give closed formulaes for the
-domination number, the distance- domination number, the independence
domination number, the domatic number and the idomatic number of corona graphs.Comment: 18 page