This article is cited in
4 papers
The normalizer of the elementary linear group of a module arising under extension of the base ring
N. H. T. Nhat,
T. N. Hoi Faculty of Mathematics and Computer Science, University of Science, VNU-HCM, 227 Nguyen Van Cu Str., Dist. 5, Ho Chi Minh City, Vietnam
Abstract:
Let
$S$ be a commutative ring with
$1$ and
$R$ a unital subring. Let
$M$ be a free
$S$-module of rank
$n\geq3$. In [1], V. A. Koibaev described the normalizer of
$\operatorname{Aut}_S(M)$ in the group
$\operatorname{Aut}_R(M)$. In this paper, we show that in
$\operatorname{Aut}_R(M)$ the normalizer of the elementary linear group
$E_\mathfrak B(M)$ coincides with the one of
$\operatorname{Aut}_S(M)$, namely, $N_{\operatorname{Aut}_R(M)}(E_\mathfrak B(M))=\operatorname{Aut}(S/R)\ltimes\operatorname{Aut}_S(M)$. If
$S$ is free of rank
$m$ as an
$R$-module, then $N_{\operatorname{GL}(mn,R)}(E(n,S))=\operatorname{Aut}(S/R)\ltimes\operatorname{GL}(n,S)$, moreover, for any proper ideal
$A$ of
$R$, we have
$$
N_{\operatorname{GL}(mn, R)}(E(n,S)E(mn,R,A))=\rho_A^{-1}(N_{\operatorname{GL}(mn,R/A)}(E(n,S/SA))).
$$
Key words and phrases:
automorphism group of a module, lattice of subgroups, ring extension subgroup, normalizer.
UDC:
512.743 Received: 05.04.2017
Language: English