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The colouring number of infinite graphs. (arXiv:1512.02911v2 [math.CO] UPDATED)
来源于:arXiv
We show that, given an infinite cardinal $\mu$, a graph has colouring number
at most $\mu$ 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. 查看全文>>