Galois theory: Main theorem
Channel: Richard E Borcherds
Date: 2021-01-04

This lecture is part of an online graduate course on Galois theory.

We prove the main theorem of Galois theory, given a bijection between subgroups of a Galois group and subextensions of a Galois extension. We illustrate it with the example of the splitting field of 4th roots of 2.