Galois Theory of Commutative Ring Spectra

Abstract: This thesis discusses Galois theory of ring spectra in the sense of John Rognes. The aim is to give a clear introduction that provides a solid foundation for further studies into the subject. We introduce ring spectra using the symmetric spectra of Hovey, Shipley and Smith, and discuss the symmetric monoidal model structure on this category. We define and give results for Galois extensions of these objects. We also give examples involving Eilenberg-Mac Lane spectra of commutative rings, topological K-theory spectra and cochain algebras of these. Galois extensions of ring spectra are compared to Ga-lois extensions of commutative rings especially relating to faithfulness, a property that is implicit in the latter, but not in the former. This is proven by looking at extensions of cochain algebras using Eilenberg-Mac Lane spectra. We end by contrasting this to cochain algebra extensions using K-theory spectra, and show that such extensions are not Galois, using methods of Baker and Richter.