## Abstract We study classes of finite, simple, undirected graphs that are (1) lower ideals (or hereditary) in the partial order of graphs by the induced subgraph relation ≤~i~, and (2) well‐quasi‐ordered (WQO) by this relation. The main result shows that the class of cographs (__P~4~__‐free graphs
Subgraphs and well-quasi-ordering
✍ Scribed by Guoli Ding
- Publisher
- John Wiley and Sons
- Year
- 1992
- Tongue
- English
- Weight
- 712 KB
- Volume
- 16
- Category
- Article
- ISSN
- 0364-9024
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✦ Synopsis
Abstract
Let 𝒴 be a class of graphs and let ⪯ be the subgraph or the induced subgraph relation. We call ⪯ an ideal (with respect to ⪯) if ⪯ implies that ⪯. In this paper, we study the ideals that are well‐quasiordered by ⪯. The following are our main results. If ⪯ is the subgraph relation, we characterize the well‐quasi‐ordered ideals in terms of exluding subgraphs. If⪯is the induced subgraph relation, we present three wellquasi‐ordered ideals. We also construct examples to disprove some of the possible generalizations of our results. The connections between some of our results and digraphs are considered in this paper too.
📜 SIMILAR VOLUMES
We study bipartite graphs partially ordered by the induced subgraph relation. Our goal is to distinguish classes of bipartite graphs that are or are not well-quasi-ordered (wqo) by this relation. Answering an open question from [J Graph Theory 16 (1992), 489-502], we prove that P 7 -free bipartite g