用强单投射模与强单内射模,给出V-环与半单环的新的刻画,证明R是左单投射遗传环,当且仅当每个单模的内射维数至多为1;R是左单内射遗传环,当且仅当每个单模的投射维数至多为1。
New characterizations of V-rings and semi-simple rings are obtained by using strong simple projective modules and strong simple injective modules. It is shown that R is left simple projective heredi- tary if and only if every simple module has the injective dimension at most 1 ; R is left simple injective he- reditary if and only if the projective dimension of every simple module is at most 1.