Abstract
In this paper we probe the possibilities of creating a Kurepa tree in a generic extension of a ground model of CH plus no Kurepa trees by an ω1 -preserving forcing notion of size at most ω1 In Section 1 we show that in the Lévy model obtained by collapsing all cardinals between ω1 and a strongly inaccessible cardinal by forcing with a countable support Lévy collapsing order, many ω1-preserving forcing notions of size at most ω1 including all ω-proper forcing notions and some proper but not ω-proper forcing notions of size at most ω1 do not create Kurepa trees. In Section 2 we construct a model of CH plus no Kurepa trees, in which there is an ω-distributive Aronszajn tree such that forcing with that Aronszajn tree does create a Kurepa tree in the generic extension. At the end of the paper we ask three questions.
Original language | English |
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Pages (from-to) | 47-68 |
Number of pages | 22 |
Journal | Annals of Pure and Applied Logic |
Volume | 85 |
Issue number | 1 |
DOIs | |
State | Published - 29 Apr 1997 |