A ring $R$ is called right P-injective if every homomorphism from a principal right ideal of $R$ to $R_R$ can be extended to a homomorphism from $R_R$ to $R_R$. Let $R$ be a ring and $G$ a group. Based on a result of Nicholson and Yousif, we prove that the group ring ${\rm RG}$ is right P-injective if and only if (a) $R$ is right P-injective; (b) $G$ is locally finite; and (c) for any finite subgroup $H$ of $G$ and any principal right ideal $I$ of ${\rm RH}$, if $f\in {\rm Hom}_R(I_R, R_R)$, then there exists $g\in {\rm Hom}_R({\rm RH}_R, R_R)$ such that $g|_I=f$. Similarly, we also obtain equivalent characterizations of $n$-injective group rings and F-injective group rings.
A ring $R$ is called right P-injective if every homomorphism from a principal right ideal of $R$ to $R_R$ can be extended to a homomorphism from $R_R$ to $R_R$. Let $R$ be a ring and $G$ a group. Based on a result of Nicholson and Yousif, we prove that the group ring ${\rm RG}$ is right P-injective if and only if (a) $R$ is right P-injective; (b) $G$ is locally finite; and (c) for any finite subgroup $H$ of $G$ and any principal right ideal $I$ of ${\rm RH}$, if $f\in {\rm Hom}_R(I_R, R_R)$, then there exists $g\in {\rm Hom}_R({\rm RH}_R, R_R)$ such that $g|_I=f$. Similarly, we also obtain equivalent characterizations of $n$-injective group rings and F-injective group rings.
@article{10_21136_CMJ_2020_0159_19,
author = {Shen, Liang},
title = {P-injective group rings},
journal = {Czechoslovak Mathematical Journal},
pages = {1103--1109},
year = {2020},
volume = {70},
number = {4},
doi = {10.21136/CMJ.2020.0159-19},
mrnumber = {4181799},
language = {en},
url = {http://geodesic.mathdoc.fr/articles/10.21136/CMJ.2020.0159-19/}
}
TY - JOUR
AU - Shen, Liang
TI - P-injective group rings
JO - Czechoslovak Mathematical Journal
PY - 2020
SP - 1103
EP - 1109
VL - 70
IS - 4
UR - http://geodesic.mathdoc.fr/articles/10.21136/CMJ.2020.0159-19/
DO - 10.21136/CMJ.2020.0159-19
LA - en
ID - 10_21136_CMJ_2020_0159_19
ER -
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