570 research outputs found

    Distinguishing colorings of graphs and their subgraphs

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    In this paper, several distinguishing colorings of graphs are studied, such as vertex distinguishing proper edge coloring, adjacent vertex distinguishing proper edge coloring, vertex distinguishing proper total coloring, adjacent vertex distinguishing proper total coloring. Finally, some related chromatic numbers are determined, especially the comparison of the correlation chromatic numbers between the original graph and the subgraphs are obtained

    Graph Colorings with Constraints

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    A graph is a collection of vertices and edges, often represented by points and connecting lines in the plane. A proper coloring of the graph assigns colors to the vertices, edges, or both so that proximal elements are assigned distinct colors. Here we examine results from three different coloring problems. First, adjacent vertex distinguishing total colorings are proper total colorings such that the set of colors appearing at each vertex is distinct for every pair of adjacent vertices. Next, vertex coloring total weightings are an assignment of weights to the vertices and edges of a graph so that every pair of adjacent vertices have distinct weight sums. Finally, edge list multi-colorings consider assignments of color lists and demands to edges; edges are colored with a subset of their color list of size equal to its color demand so that adjacent edges have disjoint sets. Here, color sets consisting of measurable sets are considered

    Asymmetric 22-colorings of graphs

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    We show that the edges of every 3-connected planar graph except K4K_4 can be colored with two colors in such a way that the graph has no color preserving automorphisms. Also, we characterize all graphs which have the property that their edges can be 22-colored so that no matter how the graph is embedded in any orientable surface, there is no homeomorphism of the surface which induces a non-trivial color preserving automorphism of the graph

    Color-blind index in graphs of very low degree

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    Let c:E(G)[k]c:E(G)\to [k] be an edge-coloring of a graph GG, not necessarily proper. For each vertex vv, let cˉ(v)=(a1,,ak)\bar{c}(v)=(a_1,\ldots,a_k), where aia_i is the number of edges incident to vv with color ii. Reorder cˉ(v)\bar{c}(v) for every vv in GG in nonincreasing order to obtain c(v)c^*(v), the color-blind partition of vv. When cc^* induces a proper vertex coloring, that is, c(u)c(v)c^*(u)\neq c^*(v) for every edge uvuv in GG, we say that cc is color-blind distinguishing. The minimum kk for which there exists a color-blind distinguishing edge coloring c:E(G)[k]c:E(G)\to [k] is the color-blind index of GG, denoted dal(G)\operatorname{dal}(G). We demonstrate that determining the color-blind index is more subtle than previously thought. In particular, determining if dal(G)2\operatorname{dal}(G) \leq 2 is NP-complete. We also connect the color-blind index of a regular bipartite graph to 2-colorable regular hypergraphs and characterize when dal(G)\operatorname{dal}(G) is finite for a class of 3-regular graphs.Comment: 10 pages, 3 figures, and a 4 page appendi
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