The ultrafilter number and hm

被引:0
|
作者
Guzman, Osvaldo [1 ]
机构
[1] UNAM, Ctr Ciencias Matemat, Morelia, Michoacan, Mexico
关键词
Cardinal invariants of the continuum; continous colorings; ultrafilters; ultrafilter number; iterated forcing; MAD families;
D O I
10.4153/S0008414X21000614
中图分类号
O1 [数学];
学科分类号
0701 ; 070101 ;
摘要
The cardinal invariant hm is defined as the minimum size of a family of c(min)-monochromatic sets that cover 2(omega) (where c(min)(x, y) is the parity of the biggest initial segment both x and y have in common). We prove that hm = omega(1) holds in Shelah's model of i < u, so the inequality hm < u is consistent with the axioms of ZFC. This answers a question of Thilo Weinert. We prove that the diamond principle lozenge(d) also holds in that model.
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页码:494 / 530
页数:37
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