是右半遗传环当且仅当任一右R模的两个上平坦子模的和上平坦；

R is semihereditary ring if and only if the sum of two coflat submodules of every R module is coflat module;

youdao

是右半遗传环当且仅当任一右R模的两个上平坦子模的和上平坦；

R is semihereditary ring if and only if the sum of two coflat submodules of every R module is coflat module;

youdao