In this paper,we consider some generalizations of tilting torsion classes and cotilting torsion-free classes,give the definition and characterizations of n-tilting torsion classes and n-cotilting torsion-free classes,...In this paper,we consider some generalizations of tilting torsion classes and cotilting torsion-free classes,give the definition and characterizations of n-tilting torsion classes and n-cotilting torsion-free classes,and study n-tilting preenvelopes and n-cotilting precovers.展开更多
Let G be a finitely generated torsion-free nilpotent group and a an automorphism of prime order p of G. If the map ψ ： G → G defined by g^φ = [g, α] is surjective, then the nilpotent class of G is at most h（p）,...Let G be a finitely generated torsion-free nilpotent group and a an automorphism of prime order p of G. If the map ψ ： G → G defined by g^φ = [g, α] is surjective, then the nilpotent class of G is at most h（p）, where h（p） is a function depending only on p. In particular, if α^3 = 1, then the nilpotent class of G is at most 2.展开更多
This paper gives an explicit formula for calculating the Webster pseudo torsion for a strictly pseudoconvex pseudo-hermitian hypersurface. As applications, we are able to classify some pseudo torsion-free hypersurface...This paper gives an explicit formula for calculating the Webster pseudo torsion for a strictly pseudoconvex pseudo-hermitian hypersurface. As applications, we are able to classify some pseudo torsion-free hypersurfaces, which include real ellipsoids.展开更多
In this paper we characterize all the lexsegment ideals which are normally torsion-free. This will provide a large class of normally torsion-free monomial ideals which are not square-free. Our characterization is give...In this paper we characterize all the lexsegment ideals which are normally torsion-free. This will provide a large class of normally torsion-free monomial ideals which are not square-free. Our characterization is given in terms of the ends of the lexsegment. We also prove that, for lexsegment ideals, the property being normally torsion-free is equivalent to the property of the depth function being constant.展开更多
An abelian group A is called a TI-group if every associative ring with the additive group A is filial.The filiality of a ring R means that the ring R is associative and all ideals of any ideal of R are ideals in R.In ...An abelian group A is called a TI-group if every associative ring with the additive group A is filial.The filiality of a ring R means that the ring R is associative and all ideals of any ideal of R are ideals in R.In this paper,torsion-free TI-groups are described up to the structure of associative nil groups.It is also proved that,for torsion-free abelian groups that are not associative nil,the condition TI implies the indecomposability and homogeneity.The paper contains constructions of 2^(■o)such groups of any rank from 2to 2^(■o)which are pairwise non-isomorphic.展开更多
基金Supported by the 2018 Scientific Research Projects in Universities of Gansu Province(2018A-269)
文摘In this paper,we consider some generalizations of tilting torsion classes and cotilting torsion-free classes,give the definition and characterizations of n-tilting torsion classes and n-cotilting torsion-free classes,and study n-tilting preenvelopes and n-cotilting precovers.
基金The NSF(11371124)of Chinathe NSF(F2015402033)of Hebei Provincethe Doctoral Special Foundation(20120066)of Hebei University of Engineering
文摘Let G be a finitely generated torsion-free nilpotent group and a an automorphism of prime order p of G. If the map ψ ： G → G defined by g^φ = [g, α] is surjective, then the nilpotent class of G is at most h（p）, where h（p） is a function depending only on p. In particular, if α^3 = 1, then the nilpotent class of G is at most 2.
文摘This paper gives an explicit formula for calculating the Webster pseudo torsion for a strictly pseudoconvex pseudo-hermitian hypersurface. As applications, we are able to classify some pseudo torsion-free hypersurfaces, which include real ellipsoids.
文摘In this paper we characterize all the lexsegment ideals which are normally torsion-free. This will provide a large class of normally torsion-free monomial ideals which are not square-free. Our characterization is given in terms of the ends of the lexsegment. We also prove that, for lexsegment ideals, the property being normally torsion-free is equivalent to the property of the depth function being constant.
文摘An abelian group A is called a TI-group if every associative ring with the additive group A is filial.The filiality of a ring R means that the ring R is associative and all ideals of any ideal of R are ideals in R.In this paper,torsion-free TI-groups are described up to the structure of associative nil groups.It is also proved that,for torsion-free abelian groups that are not associative nil,the condition TI implies the indecomposability and homogeneity.The paper contains constructions of 2^(■o)such groups of any rank from 2to 2^(■o)which are pairwise non-isomorphic.
