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In the mathematical field of graph theory, a quartic graph is a graph where all vertices have degree 4. In other words, a quartic graph is a 4-regular graph.〔.〕 ==Examples== Several well-known graphs are quartic. They include: *The complete graph ''K''5, a quartic graph with 5 vertices, the smallest possible quartic graph. *The Chvátal graph, another quartic graph with 12 vertices, the smallest quartic graph that both has no triangles and cannot be colored with three colors.〔.〕 *The Folkman graph, a quartic graph with 20 vertices, the smallest semi-symmetric graph.〔.〕 *The Meredith graph, a quartic graph with 70 vertices that is 4-connected but has no Hamiltonian cycle, disproving a conjecture of Crispin Nash-Williams.〔.〕 Every medial graph is a quartic plane graph, and every quartic plane graph is the medial graph of a pair of dual plane graphs or multigraphs.〔.〕 Knot diagrams and link diagrams are also quartic plane multigraphs, in which the vertices represent the crossings of the diagram and are marked with additional information concerning which of the two branches of the knot crosses the other branch at that point.〔.〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Quartic graph」の詳細全文を読む スポンサード リンク
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