The Colouring Number of Infinite Graphs
We show that, given an infinite cardinal μ , a graph has colouring number at most μ if and only if it contains neither of two types of subgraph. We also show that every graph with infinite colouring number has a well-ordering of its vertices that simultaneously witnesses its colouring number and its...
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Veröffentlicht in: | Combinatorica (Budapest. 1981) 2019-12, Vol.39 (6), p.1225-1235 |
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Hauptverfasser: | , , , |
Format: | Artikel |
Sprache: | eng |
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Online-Zugang: | Volltext |
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Zusammenfassung: | We show that, given an infinite cardinal
μ
, a graph has colouring number at most
μ
if and only if it contains neither of two types of subgraph. We also show that every graph with infinite colouring number has a well-ordering of its vertices that simultaneously witnesses its colouring number and its cardinality. |
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ISSN: | 0209-9683 1439-6912 |
DOI: | 10.1007/s00493-019-4045-9 |