We introduce nil 3-Armendariz rings, which are generalization of 3-Armendariz rings and nil Armendaiz rings and investigate their properties. We show that a ring R is nil 3-Armendariz ring if and only if for any , Tn(...We introduce nil 3-Armendariz rings, which are generalization of 3-Armendariz rings and nil Armendaiz rings and investigate their properties. We show that a ring R is nil 3-Armendariz ring if and only if for any , Tn(R) is nil 3-Armendariz ring. Also we prove that a right Ore ring R is nil 3-Armendariz if and only if so is Q, where Q is the classical right quotient ring of R. With the help of this result, we can show that a commutative ring R is nil 3-Armendariz if and only if the total quotient ring of R is nil 3-Armendariz.展开更多
For a local commutative Gorenstein ring R,Enochs et al.in[Gorenstein projective resolvents,Comm.Algebra 44(2016)3989-4000)defined a functor Extn^(R)(-,-)and showed that this functor can be computed by taking a totally...For a local commutative Gorenstein ring R,Enochs et al.in[Gorenstein projective resolvents,Comm.Algebra 44(2016)3989-4000)defined a functor Extn^(R)(-,-)and showed that this functor can be computed by taking a totally acyclic complex arising from a projective coresolution of the first component or a totally acyclic complex arising from a projective resolution of the second component.In order to define the functor Extn^(R)(-,-)over general rings,we introduce the right Gorenstein projective dimension of an R-module M,RGpd(M),via Gorenstein projective coresolutions,and give some equivalent characterizations for the finiteness of RGpd(M).Then over a general ring R we define a co-Tate homology group Extn^(R)(-,-) for R-modules M and N with RGpd(M)<oo and Gpd(N)<∞,and prove that Extn^(R)(M,N)can be computed by complete projective coresolutions of the first variable or by complete projective resolutions of the second variable.展开更多
This paper introduces the notion of depth with respect to ideals for unbounded DG-modules,and gives a reduction formula and the local nature of this depth.As applications,we provide several bounds of the depth in spec...This paper introduces the notion of depth with respect to ideals for unbounded DG-modules,and gives a reduction formula and the local nature of this depth.As applications,we provide several bounds of the depth in special cases,and recover and generalize the known results about the depth of complexes.In addition,the width with respect to ideals for unbounded DG-modules is investigated and the depth and width formulas for DG-modules are generalized.展开更多
Let R→S be a ring homomorphism and X be a complex of R-modules.Then the complex of S-modules S L RX in the derived category D(S)is constructed in the natural way.This paper is devoted to dealing with the relationship...Let R→S be a ring homomorphism and X be a complex of R-modules.Then the complex of S-modules S L RX in the derived category D(S)is constructed in the natural way.This paper is devoted to dealing with the relationships of the Gorenstein projective dimension of an R-complex X(possibly unbounded)with those of the S-complex S■R^L X.It is shown that if R is a Noetherian ring of finite Krull dimension and :R→S is a faithfully flat ring homomorphism,then for any homologically degree-wise finite complex X,there is an equality GpdRX=GpdS(S■R^LX).Similar result is obtained for Ding projective dimension of the S-complex S■R^L X.展开更多
文摘We introduce nil 3-Armendariz rings, which are generalization of 3-Armendariz rings and nil Armendaiz rings and investigate their properties. We show that a ring R is nil 3-Armendariz ring if and only if for any , Tn(R) is nil 3-Armendariz ring. Also we prove that a right Ore ring R is nil 3-Armendariz if and only if so is Q, where Q is the classical right quotient ring of R. With the help of this result, we can show that a commutative ring R is nil 3-Armendariz if and only if the total quotient ring of R is nil 3-Armendariz.
基金Supported by National Natural Science Foundation of China(Grant No.11971388).
文摘For a local commutative Gorenstein ring R,Enochs et al.in[Gorenstein projective resolvents,Comm.Algebra 44(2016)3989-4000)defined a functor Extn^(R)(-,-)and showed that this functor can be computed by taking a totally acyclic complex arising from a projective coresolution of the first component or a totally acyclic complex arising from a projective resolution of the second component.In order to define the functor Extn^(R)(-,-)over general rings,we introduce the right Gorenstein projective dimension of an R-module M,RGpd(M),via Gorenstein projective coresolutions,and give some equivalent characterizations for the finiteness of RGpd(M).Then over a general ring R we define a co-Tate homology group Extn^(R)(-,-) for R-modules M and N with RGpd(M)<oo and Gpd(N)<∞,and prove that Extn^(R)(M,N)can be computed by complete projective coresolutions of the first variable or by complete projective resolutions of the second variable.
基金supported by National Natural Science Foundation of China(11761060,11901463,12061061)Science and Technology project of Gansu province(20JR5RA517)+1 种基金Innovation Ability Enhancement Project of Gansu Higher Education Institutions(2019A-002)Improvement of Young Teachers’Scientific Research Ability(NWNU-LKQN-18-30).
文摘This paper introduces the notion of depth with respect to ideals for unbounded DG-modules,and gives a reduction formula and the local nature of this depth.As applications,we provide several bounds of the depth in special cases,and recover and generalize the known results about the depth of complexes.In addition,the width with respect to ideals for unbounded DG-modules is investigated and the depth and width formulas for DG-modules are generalized.
基金supported by the National Natural Science Foundation of China(Nos.11261050,11561061).
文摘Let R→S be a ring homomorphism and X be a complex of R-modules.Then the complex of S-modules S L RX in the derived category D(S)is constructed in the natural way.This paper is devoted to dealing with the relationships of the Gorenstein projective dimension of an R-complex X(possibly unbounded)with those of the S-complex S■R^L X.It is shown that if R is a Noetherian ring of finite Krull dimension and :R→S is a faithfully flat ring homomorphism,then for any homologically degree-wise finite complex X,there is an equality GpdRX=GpdS(S■R^LX).Similar result is obtained for Ding projective dimension of the S-complex S■R^L X.
