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In graph theory, the graph bandwidth problem is to label the ''n'' vertices ''vi'' of a graph ''G'' with distinct integers ''f''(''vi'') so that the quantity is minimized (''E'' is the edge set of ''G''). The problem may be visualized as placing the vertices of a graph at distinct integer points along the ''x''-axis so that the length of the longest edge is minimized. Such placement is called linear graph arrangement, linear graph layout or linear graph placement.〔 The weighted graph bandwidth problem is a generalization wherein the edges are assigned weights ''wij'' and the cost function to be minimized is . In terms of matrices, the (unweighted) graph bandwidth is the bandwidth of the symmetric matrix which is the adjacency matrix of the graph. The bandwidth may also be defined as one less than the maximum clique size in a proper interval supergraph of the given graph, chosen to minimize its clique size . ==Bandwidth formulas for some graphs== For several families of graphs, the bandwidth is given by an explicit formula. The bandwidth of a path graph ''P''''n'' on ''n'' vertices is 1, and for a complete graph ''K''''m'' we have . For the complete bipartite graph ''K''''m'',''n'', :, assuming which was proved by Chvátal.〔A remark on a problem of Harary. V. Chvátal, ''Czechoslovak Mathematical Journal'' 20(1):109–111, 1970. (http://dml.cz/dmlcz/100949 )〕 As a special case of this formula, the star graph on ''k'' + 1 vertices has bandwidth . For the hypercube graph on vertices the bandwidth was determined by to be : Chvatálová showed〔Optimal Labelling of a product of two paths. J. Chvatálová, ''Discrete Mathematics'' 11, 249–253, 1975.〕 that the bandwidth of the ''m'' × ''n'' square grid graph , that is, the Cartesian product of two path graphs on and vertices, is equal to min. 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「Graph bandwidth」の詳細全文を読む スポンサード リンク
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