New York Journal of Mathematics
Volume 17 (2011) 799-810

  

Paul J. Truman

Towards a generalisation of Noether's theorem to nonclassical Hopf-Galois structures

view    print


Published: December 17, 2011
Keywords: Noether's theorem, Hopf-Galois structures, domestic extensions
Subject: 11R33 (primary), 11S23 (secondary)

Abstract
We study the nonclassical Hopf-Galois module structure of rings of algebraic integers in some extensions of p-adic fields and number fields which are at most tamely ramified. We show that if L/K is an unramified extension of p-adic fields which is H-Galois for some Hopf algebra H then OL is free over its associated order AH in H. If H is commutative, we show that this conclusion remains valid in ramified extensions of p-adic fields if p does not divide the degree of the extension. By combining these results we prove a generalisation of Noether's theorem to nonclassical Hopf-Galois structures on domestic extensions of number fields.

Author information

School of Computing and Mathematics, Keele University, UK
P.J.Truman@Keele.ac.uk