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  2. Graph labeling - Wikipedia

    en.wikipedia.org/wiki/Graph_labeling

    Harmonious labeling. A "harmonious labeling" on a graph G is an injection from the vertices of G to the group of integers modulo k, where k is the number of edges of G, that induces a bijection between the edges of G and the numbers modulo k by taking the edge label for an edge (x, y) to be the sum of the labels of the two vertices x, y (mod k ...

  3. Graceful labeling - Wikipedia

    en.wikipedia.org/wiki/Graceful_labeling

    A graceful labeling. Vertex labels are in black, edge labels in red.. In graph theory, a graceful labeling of a graph with m edges is a labeling of its vertices with some subset of the integers from 0 to m inclusive, such that no two vertices share a label, and each edge is uniquely identified by the absolute difference between its endpoints, such that this magnitude lies between 1 and m ...

  4. Tree (graph theory) - Wikipedia

    en.wikipedia.org/wiki/Tree_(graph_theory)

    v − 1. Chromatic number. 2 if v > 1. Table of graphs and parameters. In graph theory, a tree is an undirected graph in which any two vertices are connected by exactly one path, or equivalently a connected acyclic undirected graph. [1] A forest is an undirected graph in which any two vertices are connected by at most one path, or equivalently ...

  5. Edge-graceful labeling - Wikipedia

    en.wikipedia.org/wiki/Edge-graceful_labeling

    A graph G is said to be edge-graceful if it admits an edge-graceful labeling. Examples Cycles An edge-graceful labeling of C 5. Consider the cycle with three vertices, C 3. This is simply a triangle. One can label the edges 1, 2, and 3, and check directly that, along with the induced labeling on the vertices, this gives an edge-graceful labeling.

  6. Graph coloring - Wikipedia

    en.wikipedia.org/wiki/Graph_coloring

    Graph coloring. A proper vertex coloring of the Petersen graph with 3 colors, the minimum number possible. In graph theory, graph coloring is a special case of graph labeling; it is an assignment of labels traditionally called "colors" to elements of a graph subject to certain constraints. In its simplest form, it is a way of coloring the ...

  7. List of graph theory topics - Wikipedia

    en.wikipedia.org/wiki/List_of_graph_theory_topics

    Total graph. Tree (graph theory). Trellis (graph) Turán graph. Ultrahomogeneous graph. Vertex-transitive graph. Visibility graph. Museum guard problem. Wheel graph.

  8. Graph isomorphism - Wikipedia

    en.wikipedia.org/wiki/Graph_isomorphism

    Under another definition, an isomorphism is an edge-preserving vertex bijection which preserves equivalence classes of labels, i.e., vertices with equivalent (e.g., the same) labels are mapped onto the vertices with equivalent labels and vice versa; same with edge labels. For example, the graph with the two vertices labelled with 1 and 2 has a ...

  9. Mixed graph - Wikipedia

    en.wikipedia.org/wiki/Mixed_graph

    A walk in a mixed graph is a sequence of vertices and edges/arcs such that for every index , either is an edge of the graph or is an arc of the graph. This walk is a path if it does not repeat any edges, arcs, or vertices, except possibly the first and last vertices. A walk is closed if its first and last vertices are the same, and a closed ...