Nonnil-FP-injective and nonnil-FP-projective dimensions and nonnil-semihereditary rings

Abstract

In this paper, we introduce the concept of nonnil-FP-injective dimension for both modules and rings. We explore the characterization of strongly $$\phi $$ ϕ -rings that have a nonnil-FP-injective dimension of at most one. We demonstrate that, for a nonnil-coherent, strongly $$\phi $$ ϕ -ring R, the nonnil-FP-injective dimension of R corresponds to the supremum of the $$\phi $$ ϕ -projective dimensions of specific families of R-modules. We also define self-nonnil-injective rings as $$\phi $$ ϕ -rings that act as nonnil semi-injective modules over themselves and establish the equivalence between a strongly $$\phi $$ ϕ -ring R being $$\phi $$ ϕ -von Neumann regular and R being both nonnil-coherent and self-nonnil semi-injective. Furthermore, we extend the notion of semihereditary rings to $$\phi $$ ϕ -rings, coining the term ‘nonnil-semihereditary’ to describe rings where every finitely generated nonnil ideal is u-$$\phi $$ ϕ -projective. We provide several characterizations of nonnil-semihereditary rings through various conceptual lenses. Our study also includes an investigation of the transfer of the nonnil-semihereditary property in trivial ring extensions. Additionally, we define the nonnil-FP-projective dimension for modules and rings, showing that for any strongly $$\phi $$ ϕ -ring, a nonnil-FP-projective dimension of zero is indicative of the ring being nonnil-Noetherian. We also ascertain that, for a strongly $$\phi $$ ϕ -ring R, its nonnil-FP-projective dimension is the supremum of the NFP-projective dimensions across different families of R-modules. Lastly, we provide numerous examples to illustrate our results.