Vyacheslav Artamonov | Searcharxiv

arXiv2015

Extended modules and Ore extensions

In this paper we investigate extended modules for a special class of Ore extensions. We will assume that $R$ is a ring and $A$ will denote the Ore extension $A:=R[x_1,\dots,x_n;σ]$ for which $σ$ is an automorphism of $R$, $x_ix_j=x_jx_i$ and $x_ir=σ(r)x_i$, for every $1\leq i,j\leq n$. With some extra conditions over the ring $R$, we will prove Vaserstein's, Quillen's patching, Horrocks' and Quillen-Suslin's theorems for this type of non-commutative rings.

math.RA↗

arXiv1996

Actions of Pointed Hopf Algebras

Action of finite-dimensional Hopf algebra $H$ on commutative $k-$algebra $A$ is considered. As a generalization of the well-known fact for finite groups S. Montgomery raised a problem in 1993 whether $A$ is integral over subalgebra of invariants $A^H$. Recently some new results were obtained. Using the properties of coradical filtration of pointed Hopf algebras we verified the truth of the hypothesis in tree different cases: 1) Hopf algebra $H$ is commutative; 2) char $k = p > 0$; 3) $A$ is integral domain. In spite of numerous partial positive results it turned out that hypothesis of S. Montgomery isn't true in general. The counteraxamples were built for series of pointed Hopf algebras $A_N, N \ge 2$.

q-alg↗