Abstract:
Let $R$ be a ring. This paper introduces and studies $\mathcal{GP}$-projective and $\mathcal{GI}$-injective left $R$-modules. Our main goal is to investigate the “global” dimension
$$
\operatorname{GPID}(R)=\sup\{\operatorname{id}(M)\mid M\in{_R\mathcal{M}},\,\text{$M$ is Gorenstein projective}\}.
$$