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  2. Line graph - Wikipedia

    en.wikipedia.org/wiki/Line_graph

    In the mathematical discipline of graph theory, the line graph of an undirected graph G is another graph L(G) that represents the adjacencies between edges of G. L(G) is constructed in the following way: for each edge in G, make a vertex in L(G); for every two edges in G that have a vertex in common, make an edge between their corresponding vertices in L(G).

  3. Halin's grid theorem - Wikipedia

    en.wikipedia.org/wiki/Halin's_grid_theorem

    In graph theory, a branch of mathematics, Halin's grid theorem states that the infinite graphs with thick ends are exactly the graphs containing subdivisions of the hexagonal tiling of the plane. [1] It was published by Rudolf Halin ( 1965 ), and is a precursor to the work of Robertson and Seymour linking treewidth to large grid minors , which ...

  4. Graph theory - Wikipedia

    en.wikipedia.org/wiki/Graph_theory

    In mathematics and computer science, graph theory is the study of graphs, which are mathematical structures used to model pairwise relations between objects. A graph in this context is made up of vertices (also called nodes or points ) which are connected by edges (also called arcs , links or lines ).

  5. Glossary of graph theory - Wikipedia

    en.wikipedia.org/wiki/Glossary_of_graph_theory

    quasi-line graph A quasi-line graph or locally co-bipartite graph is a graph in which the open neighborhood of every vertex can be partitioned into two cliques. These graphs are always claw-free and they include as a special case the line graphs. They are used in the structure theory of claw-free graphs. quasi-random graph sequence

  6. Kirkman's schoolgirl problem - Wikipedia

    en.wikipedia.org/wiki/Kirkman's_schoolgirl_problem

    Kirkman himself gave a solution [8] that later would be found to be isomorphic to Solution I above. Kirkman claimed it to be the only possible solution but that was incorrect. Arthur Cayley's solution [9] would be later found to be isomorphic to Solution II. Both solutions could be embedded in PG(3,2) though that geometry was not known at the ...

  7. Fáry's theorem - Wikipedia

    en.wikipedia.org/wiki/Fáry's_theorem

    In the mathematical field of graph theory, Fáry's theorem states that any simple, planar graph can be drawn without crossings so that its edges are straight line segments. That is, the ability to draw graph edges as curves instead of as straight line segments does not allow a larger class of graphs to be drawn.

  8. Path (graph theory) - Wikipedia

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

    A three-dimensional hypercube graph showing a Hamiltonian path in red, and a longest induced path in bold black. In graph theory, a path in a graph is a finite or infinite sequence of edges which joins a sequence of vertices which, by most definitions, are all distinct (and since the vertices are distinct, so are the edges).

  9. Theta graph - Wikipedia

    en.wikipedia.org/wiki/Theta_graph

    Example cone of a -graph emanating from with orthogonal projection line -graphs are specified with a few parameters which determine their construction. The most obvious parameter is , which corresponds to the number of equal angle cones that partition the space around each vertex. In particular, for a vertex , a cone about can be imagined as two infinite rays emanating from it with angle ...