Letter graphs and well-quasi-order by induced subgraphs
نویسندگان
چکیده
منابع مشابه
Letter graphs and well-quasi-order by induced subgraphs
Given a word w over a 1nite alphabet and a set of ordered pairs of letters which de1ne adjacencies, we construct a graph which we call the letter graph of w. The lettericity of a graph G is the least size of the alphabet permitting to obtain G as a letter graph. The set of 2-letter graphs consists of threshold graphs, unbounded-interval graphs, and their complements. We determine the lettericit...
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Given a word w over a nite alphabet and a set of ordered pairs of letters which de ne adjacencies we construct a graph which we call the letter graph of w The lettericity of a graph G is the least size of alphabet permitting to obtain G as a letter graph The set of letter graphs consists of threshold graphs unbounded interval graphs and their complements We determine the lettericity of cycles a...
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Let % be a class of graphs and let i be the subgraph or the induced subgraph relation. We call % an idea/ (with respect to I) if G I G' E % implies that G E %. In this paper, we study the ideals that are well-quasiordered by I. The following are our main results. If 5 is the subgraph relation, we characterize the well-quasi-ordered ideals in terms of excluding subgraphs. If I is the induced sub...
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ژورنال
عنوان ژورنال: Discrete Mathematics
سال: 2002
ISSN: 0012-365X
DOI: 10.1016/s0012-365x(01)00094-2