English

Vector invariants of permutation groups in characteristic zero

Commutative Algebra 2022-11-22 v1 Representation Theory

Abstract

We consider a finite permutation group acting naturally on a vector space VV over a field k\Bbbk. A well known theorem of G\"obel asserts that the corresponding ring of invariants k[V]G\Bbbk[V]^G is generated by invariants of degree at most (dimV2)\binom{\dim V}{2}. In this note we show that if the characteristic of k\Bbbk is zero then the top degree of vector coinvariants k[Vm]G\Bbbk[V^m]_G is also bounded above by (dimV2)\binom{\dim V}{2}, which implies the degree bound (dimV2)+1\binom{\dim V}{2}+ 1 for the ring of vector invariants k[Vm]G\Bbbk[V^m]^G. So G\"obel's bound almost holds for vector invariants in characteristic zero as well.

Keywords

Cite

@article{arxiv.2211.11091,
  title  = {Vector invariants of permutation groups in characteristic zero},
  author = {Fabian Reimers and Müfit Sezer},
  journal= {arXiv preprint arXiv:2211.11091},
  year   = {2022}
}

Comments

preliminary version

R2 v1 2026-06-28T06:19:29.487Z