Universality among graphs omitting a complete bipartite graph

نویسنده

  • Saharon Shelah
چکیده

For cardinals λ, κ, θ we consider the class of graphs of cardinality λ which has no subgraph which is (κ, θ)-complete bipartite graph. The question is whether in such a class there is a universal one under (weak) embedding. We solve this problem completely under GCH. Under various assumptions mostly related to cardinal arithmetic we prove non-existence of universals for this problem. We also look at combinatorial properties useful for those problems concerning κ-dense families.

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عنوان ژورنال:
  • Combinatorica

دوره 32  شماره 

صفحات  -

تاریخ انتشار 2012