English

Interplay between homological dimensions of a complex and its right derived section

Commutative Algebra 2016-07-29 v2

Abstract

Let (R,m)(R,\mathfrak{m}) be a commutative Noetherian local ring, a\mathfrak{a} be a proper ideal of RR and MM be an RR-complex in D(R)\mathrm{D}(R). We prove that if MDf(R)M\in\mathrm{D}^f_\sqsubset(R) (respectively, MDf(R)M\in\mathrm{D}^f_\sqsupset(R)), then idRRΓa(M)=idRM\mathrm{id}_R\mathbf{R}\Gamma_{\mathfrak{a}}(M)=\mathrm{id}_R M (respectively, fdRRΓa(M)=fdRM\mathrm{fd}_R\mathbf{R}\Gamma_{\mathfrak{a}}(M)=\mathrm{fd}_R M). Next, it is proved that the right derived section functor of a complex MD(R)M\in\mathrm{D}_\sqsubset(R) (RR is not necessarily local) can be computed via a genuine left-bounded complex GMG\simeq M of Gorenstein injective modules. We show that if RR has a dualizing complex and MM is an RR-complex in Df(R)\mathrm{D}^f_\square(R), then GfdRRΓa(M)=GfdRM\mathrm{Gfd}_R\mathbf{R}\Gamma_{\mathfrak{a}}(M)=\mathrm{Gfd}_R M and GidRRΓa(M)=GidRM\mathrm{Gid}_R\mathbf{R}\Gamma_{\mathfrak{a}}(M)=\mathrm{Gid}_R M. Also, we show that if MM is a relative Cohen-Macaulay RR-module with respect to a\mathfrak{a} (respectively, Cohen-Macaulay RR-module of dimension nn), then GfdRHahtMa(M)=GfdRM+n\mathrm{Gfd}_R\mathbf{H}^{\mathrm{ht_M\mathfrak{a}}}_{\mathfrak{a}}(M)=\mathrm{Gfd}_RM+n (respectively, GidRHmn(M)=GidRMn\mathrm{Gid}_R\mathbf{H}^n_{\mathfrak{m}}(M)=\mathrm{Gid}_RM-n). The above results generalize some known results and provide characterizations of Gorenstein rings.

Keywords

Cite

@article{arxiv.1404.3982,
  title  = {Interplay between homological dimensions of a complex and its right derived section},
  author = {Cyrus Jalali},
  journal= {arXiv preprint arXiv:1404.3982},
  year   = {2016}
}

Comments

9 pages, to appear in Mathematical Reports

R2 v1 2026-06-22T03:51:30.029Z