On the number of non-isomorphic subgraphs
Abstract
Let K be the family of graphs on omega1 without cliques or independent subsets of size omega1 . We prove that: 1) it is consistent with CH that every G in K has 2omega1 many pairwise non-isomorphic subgraphs, 2) the following proposition holds in L: (*) there is a G in K such that for each partition (A,B) of omega1 either G cong G[A] or G cong G[B], 3) the failure of (*) is consistent with ZFC.
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