Sequence mixed graphs

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• 作者：C. Dalfó ; ^a ; ^{cristina.dalfo@upc.edu} ; M.A. Fiol^b ; ^{miguel.angel.fiol@upc.edu} ; N. Ló ; pez^c ; ^{nlopez@matematica.udl.es}
• 关键词：Mixed graph ; Sequence graph ; Line digraph ; Degree/diameter problem ; Moore bound ; Diameter ; Mean distance
• 刊名：Discrete Applied Mathematics
• 出版年：2017
• 出版时间：11 March 2017
• 年：2017
• 卷：219
• 期：Complete
• 页码：110-116
• 全文大小：462 K
• 卷排序：219

文摘

A mixed graph can be seen as a type of digraph containing some edges (or two opposite arcs). Here we introduce the concept of sequence mixed graphs, which is a generalization of both sequence graphs and iterated line digraphs. These structures are proven to be useful in the problem of constructing dense graphs or digraphs, and this is related to the degree/diameter problem. Thus, our generalized approach gives rise to graphs that have also good ratio order/diameter. Moreover, we propose a general method for obtaining a sequence mixed digraph by identifying some vertices of a certain iterated line digraph. As a consequence, some results about distance-related parameters (mainly, the diameter and the average distance) of sequence mixed graphs are presented.