An improper arithmetically closed Borel subalgebra of P(ω) mod FIN

Ali Enayat*, Saharon Shelah

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

We show the existence of a subalgebra A⊆P(ω) that satisfies the following three conditions: A is Borel (when P(ω) is identified with 2ω). A is arithmetically closed (i.e., A is closed under the Turing jump, and Turing reducibility). The forcing notion (A,⊆) modulo the ideal FIN of finite sets collapses the continuum to א0.

Original languageEnglish
Pages (from-to)2495-2502
Number of pages8
JournalTopology and its Applications
Volume158
Issue number18
DOIs
StatePublished - 1 Dec 2011

Keywords

  • Borel structure
  • Completely separable family
  • Forcing
  • Tree indiscernible

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