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In mathematics, and particularly in graph theory, the dimension of a graph is the least integer such that there exists a "classical representation" of the graph in the Euclidean space of dimension with all the edges having unit length. In a classical representation, the vertices must be distinct points, but the edges may cross one another.〔Some mathematicians regard this strictly as an "immersion", but many graph theorists, including Erdős, Harary and Tutte, use the term "embedding".〕 The dimension of a graph is written: . For example, the Petersen graph can be drawn with unit edges in , but not in : its dimension is therefore 2 (see the figure to the right). This concept was introduced in 1965 by Paul Erdős, Frank Harary and William Tutte. It generalises the concept of unit distance graph to more than 2 dimensions. == Examples == 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「Dimension (graph theory)」の詳細全文を読む スポンサード リンク
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