L-fuzzy模范畴中的极限

本文给出了L-fuzzy模范畴中的极限有点式和无点式刻画,讨论了L-fuzzy模范畴中极限的存在性、唯一性和结构性定理,并得到了极限函子与常量系统函子的伴随性。     

L—fuzzy模范畴的张量积与张量函子

本文在Ｌ—ｆｕｚｚｙ模范畴中，建立了相应的张量积，给出了它的结构性、存在性与唯一性定理，并讨论了张量函子与Ｈｏｍ函子的伴随性。所得结果为通常张量积的“良好推广”（ｇｏｏｄｅｘｔｅｎｓｉｏｎ）。     

$D_4$型李代数包络代数旋模的范畴化

本文我们定义复数域$C$上一般线性李代数${\rm gl}_n$ BGG 范畴的若干子范畴及其上的投射函子,利用这些子范畴和投射函子范畴化了$D_4$型李代数包络代数旋模的$n$-次张量积.     

可分半群的张量积

本文建立交换可分半群范畴中的张量积,证明其存在与唯一性,同时,建立交换半群的极大可分半群象与张量积之间的关系。最后证明交换可分半群量积的极大半格象同构于其极大半格象的张量积。     

定义在范畴_RM_n~l上的张量函数

文[1]引进了左R-n模范畴_RM_n~1,将Hom函子推扩到_RM_n~l上,且讨论了它的拟正合性。在模范畴中,张量函子与Hom函子一样是一个重要的函子。文[2]企图在_RM_n~l上建立相应的张量积,并证明张量函子M_n~:AG_(rn)→_RM_n~l与Hom函子Hom(M_):AG_(rn)′→_RM_n~l为伴随对。但其构造的交换自由n-群仅对满足(E)条件的交换n-群具有泛性,故其张量积亦只是     

对偶化范畴的张量积构造

本文证明了一个局部有限箭图的路范畴模一个单项式容许理想所得的剩余范畴与一个对偶化范畴的张量积的加法包的幂等完备是对偶化的.从而,此张量积范畴的有限表现函子范畴是对偶化的且有几乎可裂序列.作为应用,本文证明了一个对偶化范畴上的有限表现函子范畴的态射范畴与态射合成范畴及各种各样的n-(循环)复形范畴有几乎可裂序列.     

函子范畴上加性函子的一个表示

研究函子范畴ModC上加性函子的表示,把一个Abel群作成范畴ModC上的一个左C-模,构造出一个Hom函子和一个函子态射,证明了从函子范畴ModC到范畴Ab的任意变和为积的反变左正合可加函子都与某个Hom函子自然等价.所得结论在函子范畴上,推广了Watts定理.     

PrO-C*-代数的顺从性和核性

研究了Pro—C^*-代数的顺从性和核性．主要证明了(1)顺从Pro—C^*代数的闭理想是顺从的；(2)核Pro—C^*代数类对归纳极限封闭；(3)交换σ-C^*-代数和核C^*-代数都是核，σ-C^*-代数并且核σ-C^*-代数类对于商运算、张量积运算和可数逆向极限封闭．进一步得到核，σ-C^*-代数的扩张保持核性的条件。     

Monoidal Entwined模范畴上的张量积恒等式

本文研究了monoidal entwined模范畴上的张量积恒等式.利用了monoidal entwined模范畴的性质及Doi-Hopf模范畴上的张量积恒等式的研究方法,获得了monoidal entwined模范畴上的一些张量积恒等式,并证明了entwined模范畴有足够的内射对象,结果推广了Doi-Hopf模范畴的结论.     

Doi-Hopf模范畴中的sovereign结构

本文研究了Doi-Hopf模范畴中的sovereign结构,引入了sovereign Doi-Hopf数组和Doi-smash积的定义,证明了Doi-smash积的表示范畴与Doi-Hopf模范畴的等价性,并给出了Doi-Hopf模范畴做成sovereign范畴的充要条件.作为应用,研究了Yetter-Drinfeld模范畴中的sovereign结构.     

On Flat Semimodules over Semirings

The following analog of the characterization of flat modules has been obtained for the variety of semimodules over a semiring R: A semimodule _RA is flat (i.e., the tensor product functor – A preserves all finite limits) iff A is L-flat (i.e., A is a filtered colimit of finitely generated free semimodules). We also give new (homological) characterizations of Boolean algebras and complete Boolean algebras within the classes of distributive lattices and Boolean algebras, respectively, which solve two problems left open in [14]. It is also shown that, in contrast with the case of modules over rings, in general for semimodules over semirings the notions of flatness and mono-.atness (i.e., the tensor product functor – A preserves monomorphisms) are different.     

Wreath Product of Set-Valued Functors and Tensor Multiplication

Considering the wreath product functor $G wr H:{\cal A} wr^G{\cal B} \rightarrow \SET$ of functors $G: {\cal A}\rightarrow \SET$ and $H: {\cal B}\rightarrow \SET$ over small categories $ {\cal A}$ and $ {\cal B}$, we prove that if tensor multiplication by the functor $G\wrr H$ preserves $ {\cal D}$-limits, where ${\cal D}$ is a small category, then tensor multiplication by $G$ preserves ${\cal D}$-limits, and if tensor multiplication by the functor $G wr H$ preserves ${\cal D}$-limits of representables then tensor multiplications by $G$ and $H$ preserve $ {\cal D}$-limits of representables. We also study flatness and pullback flatness of the wreath product of set-valued functors.     

AN ANALOGUE OF KǘNNETH THEOREM IN STRONG HOMOLOGY

After defining the strong tensor product of strong (sub)chain complexes, it is shown that an analogue of the Kunneth theorem holds in strong homology by proving that the kernel (cokernel) of connecting homomorphisms is isomorphic to the direct sum of torsion (tensor) products of strong homology groups. An isomorphism between strong (r-stage) homology groups of inverse systems is also constructed.     

AN ANALOGUE OF KüNNETH THEOREM INSTRONG HOMOLOGY

1 IntroductiouLet G and Z be an abelian group and the set Of all integers respectively And letC = (C., ft,', I') denote an inverse system of chain complexes C. and chain maPS I..1: Cv, -Ct,7 5 T' indexed by a directed set r. Strong homology groups HP(C) of the inverse systemC were defilled by J. T. Lisica and S. Mardedie[n. Using the ANRresOlution[9'l1I, algebraictopolOgists defined the strong homology group HP(X; G) of a topological space X with coefficient8 in G and gave exMPl…     

Tensor Products and Preservation of Weighted Limits,for S-Posets

We prove that the functor of tensor multiplication by a right S-poset (S is a pomonoid) preserves all small weighted limits if and only if this S-poset is cyclic and projective. We also show that this functor preserves all finite pie-limits if and only if the S-poset is a filtered colimit of S-posets isomorphic to S _S .     

Some remarks on tensor products and flatness of semimodules

Using a restrictive notion of exactness and the natural tensor product, we generalize several results related to flat modules over rings to flat semimodules over semirings.     

On skew field coproducts with a finite extension

It is shown that the field coproduct of any skew fieldE with a binomial (commutative) field extensionF/k overk can be expressed as a cyclic extension of a skew fieldK (theE-socle), itself the field coproduct of [F:k] copies ofE overk. Qua vector space the coproduct may also be expressed as a tensor product ofE andK overk. To the memory of Shimshon Amitsur     

Direct sums of injective semimodules and direct products of projective semimodules over semirings

We prove that if the direct sum of a family of semimodules over a semiring S is an injective semimodule or if the direct product of a family of semimodules over S is a projective semimodule, then the cardinality of the subfamily consisting of all semimodules which are not modules is strictly less than the cardinality of S. As a consequence, we obtain semiring analogs of well-known characterizations of classical semisimple, quasi-Frobenius, and one-sided Noetherian rings.     

Bialgebras Over Noncommutative Rings and a Structure Theorem for Hopf Bimodules

It is a key property of bialgebras that their modules have a natural tensor product. More precisely, a bialgebra over k can be characterized as an algebra H whose category of modules is a monoidal category in such a way that the underlying functor to the category of k-vector spaces is monoidal (i.e. preserves tensor products in a coherent way). In the present paper we study a class of algebras whose module categories are also monoidal categories; however, the underlying functor to the category of k-vector spaces fails to be monoidal. Instead, there is a suitable underlying functor to the category of B-bimodules over a k-algebra B which is monoidal with respect to the tensor product over B. In other words, we study algebras L such that for two L-modules V and W there is a natural tensor product, which is the tensor product V_BW over another k-algebra B, equipped with an L-module structure defined via some kind of comultiplication of L. We show that this property is characteristic for ×_B-bialgebras as studied by Sweedler (for commutative B) and Takeuchi. Our motivating example arises when H is a Hopf algebra and A an H-Galois extension of B. In this situation, one can construct an algebra L:=L(A,H), which was previously shown to be a Hopf algebra if B=k. We show that there is a structure theorem for relative Hopf bimodules in the form of a category equivalence . The category on the left hand side has a natural structure of monoidal category (with the tensor product over A) which induces the structure of a monoidal category on the right hand side. The ×_B-bialgebra structure of L that corresponds to this monoidal structure generalizes the Hopf algebra structure on L(A,H) known for B=k. We prove several other structure theorems involving L=L(A,H) in the form of category equivalences .     

Exterior Tensor Product of Perverse Sheaves

Under certain assumptions, we prove that the Deligne tensor product of the categories of constructible perverse sheaves on pseudomanifolds X and Y is the category of constructible perverse sheaves on X×Y. The functor of the exterior Deligne tensor product is identified with the exterior geometric tensor product.