The Kunen-Miller chart (Lebesgue measure, the Baire property, Laver reals and preservation theorems for forcing)

• Published in: The Journal of symbolic logic 1990-09, Vol.55 (3), p.909-927
• Main Authors: Judah, Haim, Shelah, Saharon
• Format: Article
• Language: English
• Subjects: Additivity; Borel sets; Exact sciences and technology; Induction assumption; Lebesgue measures; Logical theorems; Mathematical logic; Mathematical logic, foundations, set theory; Mathematical theorems; Mathematics; Partially ordered sets; Property titles; Sciences and techniques of general use; Set theory
• ISSN: 0022-4812; 1943-5886
• DOI: 10.2307/2274464

In this work we give a complete answer as to the possible implications between some natural properties of Lebesgue measure and the Baire property. For this we prove general preservation theorems for forcing notions. Thus we answer a decade-old problem of J. Baumgartner and answer the last three open questions of the Kunen-Miller chart about measure and category. Explicitly, in \S1: (i) We prove that if we add a Laver real, then the old reals have outer measure one. (ii) We prove a preservation theorem for countable-support forcing notions, and using this theorem we prove (iii) If we add ω2 Laver reals, then the old reals have outer measure one. From this we obtain (iv) $\operatorname{Cons}(\mathrm{ZF}) \Rightarrow \operatorname{Cons}(\mathrm{ZFC} + \neg B(m) + \neg U(m) + U(c))$. In \S2: (i) We prove a preservation theorem, for the finite support forcing notion, of the property "$F \subseteq ^\omega\omega$ is an unbounded family." (ii) We introduce a new forcing notion making the old reals a meager set but the old members of ωω remain an unbounded family. Using this we prove (iii) $\operatorname{Cons}(\mathrm{ZF}) \Rightarrow \operatorname{Cons}(\mathrm{ZFC} + U(m) + \neg B(c) + \neg U(c) + C(c))$. In \S3: (i) We prove a preservation theorem, for the finite support forcing notion, of a property which implies "the union of the old measure zero sets is not a measure zero set," and using this theorem we prove (ii) $\operatorname{Cons}(\mathrm{ZF}) \Rightarrow \operatorname{Cons}(\mathrm{ZFC} + \neg U(m) + C(m) + \neg C(c))$.