Dissertation/Thesis Abstract

Contributions to descriptive set theory
by Atmai, Rachid, Ph.D., University of North Texas, 2015, 138; 10032212
Abstract (Summary)

In this dissertation we study closure properties of pointclasses, scales on sets of reals and the models L[T2n], which are very natural canonical inner models of ZFC. We first characterize projective-like hierarchies by their associated ordinals. This solves a conjecture of Steel and a conjecture of Kechris, Solovay, and Steel. The solution to the first conjecture allows us in particular to reprove a strong partition property result on the ordinal of a Steel pointclass and derive a new boundedness principle which could be useful in the study of the cardinal structure of L(R). We then develop new methods which produce lightface scales on certain sets of reals. The methods are inspired by Jackson’s proof of the Kechris-Martin theorem. We then generalize the Kechris-Martin Theorem to all the Π12n+1 pointclasses using Jackson’s theory of descriptions. This in turns allows us to characterize the sets of reals of a certain initial segment of the models L[T2 n]. We then use this characterization and the generalization of Kechris-Martin theorem to show that the L[T2n] are unique. This generalizes previous work of Hjorth. We then characterize the L[T2n] in term of inner models theory, showing that they actually are constructible models over direct limit of mice with Woodin cardinals, a counterpart to Steel’s result that the L[T2n+1] are extender models, and finally show that the generalized contiuum hypothesis holds in these models, solving a conjecture of Woodin.

Indexing (document details)
Advisor: Jackson, Steve
School: University of North Texas
Department: Mathematics
School Location: United States -- Texas
Source: DAI-B 77/08(E), Dissertation Abstracts International
Subjects: Mathematics
Keywords: Descriptive set theory, Foundations of mathematics, Inner model theory, Logic, Set theory
Publication Number: 10032212
ISBN: 978-1-339-53388-9
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