English

Noether's problem for $p$-groups with an abelian subgroup of index $p$

Algebraic Geometry 2013-09-04 v4

Abstract

Let KK be a field and GG be a finite group. Let GG act on the rational function field K(x(g):gG)K(x(g):g\in G) by KK-automorphisms defined by gx(h)=x(gh)g\cdot x(h)=x(gh) for any g,hGg,h\in G. Denote by K(G)K(G) the fixed field K(x(g):gG)GK(x(g):g\in G)^G. Noether's problem then asks whether K(G)K(G) is rational over KK. Let pp be an odd prime and let GG be a pp-group of exponent pep^e. Assume also that {\rm (i)} char K=p>0K = p>0, or {\rm (ii)} char KpK \ne p and KK contains a primitive pep^e-th root of unity. In this paper we prove that K(G)K(G) is rational over KK for the following two types of groups: {\rm (1)} GG is a finite pp-group with an abelian normal subgroup HH of index pp, such that HH is a direct product of normal subgroups of GG of the type Cpb×(Cp)cC_{p^b}\times (C_p)^c for some b,c:1b,0cb,c:1\leq b,0\leq c; {\rm (2)} GG is any group of order p5p^5 from the isoclinic families with numbers 1,2,3,4,81,2,3,4,8 and 9.

Keywords

Cite

@article{arxiv.1201.5555,
  title  = {Noether's problem for $p$-groups with an abelian subgroup of index $p$},
  author = {Ivo M. Michailov},
  journal= {arXiv preprint arXiv:1201.5555},
  year   = {2013}
}

Comments

I added a new theorem for groups of order p^5. The paper will appear in Algebra Colloquium. arXiv admin note: text overlap with arXiv:0911.1162 by other authors