# MA3H3 Set Theory

Lecturer: Andras Mathe

Term(s): Term 1

Status for Mathematics students: List A

Commitment: 30 lectures

Assessment: 100% 3 hour exam

Formal registration prerequisites: None

Assumed knowledge: Elementary set theory and Proof by induction, as covered in:

Useful background: Set theoretic reasoning in topology, as in:

Synergies:

Content: Set theoretical concepts and formulations are pervasive in modern mathematics. For this reason it is often said that set theory provides a foundation for mathematics. Here `foundation' can have multiple meanings. On a practical level, set theoretical language is a highly useful tool for the definition and construction of mathematical objects. On a more theoretical level, the very notion of a foundation has definite philosophical overtones, in connection with the reducibility of knowledge to agreed first principles.

The module will commence with a brief review of naive set theory. Unrestricted set formation leads to various paradoxes (Russell, Cantor, Burali-Forti), thereby motivating axiomatic set theory. The Zermelo-Fraenkel system will be introduced, with attention to the precise formulation of axioms and axiom schemata, the role played by proper classes, and the cumulative hierarchy picture of the set theoretical universe. Transfinite induction and recursion, cardinal and ordinal numbers, and the real number system will all be developed within this framework. The Axiom of Choice, and various equivalents and consequences, will be discussed; various other principles also known to be independent of Zermelo-Fraenkel set theory, such as the Continuum Hypothesis and the existence of Inaccessible Cardinals, will be touched on.

Books:

• Set Theory, T. Jech (a comprehensive advanced text which goes well beyond the above syllabus)
• Notes on Set Theory, Y. Moschovakis
• Elements of Set Theory, H. Enderton
• Introduction to Set Theory, K. Hrbacek and T. Jech