# Unit information: Set Theory in 2018/19

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Unit name Set Theory MATH32000 20 H/6 Teaching Block 1 (weeks 1 - 12) Professor. Welch Not open None None School of Mathematics Faculty of Science

## Description

Unit aims

To introduce the students to the general theory of sets, as a foundational and as an axiomatic theory.

General Description of the Unit

The aim is to make the course of general interest to students who are not planning to specialize in mathematical logic or the Level M/7 Axiomatic Set Theory, but of special interest to those who are.

Set Theory can be regarded as a foundation for all, or most, of mathematics, in that any mathematical concept can be formulated as being about sets. The course shows how we can represent the natural numbers as sets and how principles such as proof by mathematical induction can be seen as being built up from very primitive notions about sets.

We shall see how the pitfalls of the various early "set theoretic paradoxes" such as that of Russell ("the set of all sets that do not contain themselves") were avoided. We develop Cantor's theory of transfinite ordinal numbers and their arithmetic through the introduction of his most substantial contribution to mathematics: the notion of wellordering. We shall see how an "arithmetic of the infinite" can be developed that extends naturally the arithmetic of the finite we all know. We shall introduce the principle of ordinal induction and recursion along the ordinals to extend that of mathematical induction and recursion along the natural numbers. Cantor's famous proof of the uncountability of the real continuum by a diagonal argument, and his revolutionary discovery that there were different "orders of infinity" - indeed infinitely many such - will feature prominently in our basic study of infinite cardinal numbers and their arithmetic.

We shall see how axiom sets can be used to develop this theory, and indeed the whole cumulative hierarchy of sets of mathematical discourse. There will be discussion of the axioms system ZF developed by Zermelo and Fraenkel in the wake of Cantor's work, and about the role the Axiom of Choice plays in set theory.

Relation to Other Units

Set Theory may be regarded as the foundation for all mathematics. This course is a prerequisite, is a for the level M/7 unit Axiomatic Set Theory M1300.

For students interested in the philosophy of mathematics: this course is related to a number of units in the philosophy department in philosophy of mathematics. It should thus be of interest to any joint Maths/Philosophy degree students, and to those on the MA in Logic and Philosophy of Mathematics

## Intended learning outcomes

Learning Objectives

The student should come away from this course with a basic understanding of such topics as the theory of partial orderings and well orderings, cardinality, ordinal numbers, and the role of the Axiom of Choice. He or she should also have become aware of the role of set theory as a foundation for mathematics, and of the part that axiomatic set theory has to play.

Transferable Skills

The ability to think more deeply about our basic assumptions and concepts.

## Teaching details

Lectures and Exercise Sheets.

## Assessment Details

100% Examination

Raw scores on the examinations will be determined according to the marking scheme written on the examination paper. The marking scheme, indicating the maximum score per question, is a guide to the relative weighting of the questions. Raw scores are moderated as described in the Undergraduate Handbook.