250100 VO Axiomatic set theory 1 (2020S)

This lecture will be an introduction to set theory, in particular to independence proofs. The goal is to establish the independence of the continuum hypothesis. We will start from the ZFC axioms and introduce ordinals and cardinals. Then we will define Gödel's constructible universe L and show that it is a model of ZFC and GCH, the generalized continuum hypothesis. Furthermore, we will introduce measurable cardinals and show that they cannot exist in L. If time allows, we will discuss variants L[U] of L which allow the existence of a measurable cardinal. Finally, we will introduce Cohen's forcing technique and show that there is a model of ZFC in which the continuum hypothesis does not hold.