关于有限生模嵌入自由模

本文利用模的H-有限生成性质刻画了具有性质任意有限生成左模是自由模的子模的环.另外,还给出了左IF-环的一个刻画.     

模丛上的嵌入子丛

利用模丛之间的嵌入关系,构造出了自由丛 的嵌入子丛和任一模丛的嵌入子自由丛. 得到一般模丛都能够成为一个自由丛 的嵌入子丛; 同时任一模丛也能够有一自由丛(或投射丛)是它的嵌入子丛; 还给出了投射丛转化为自由丛的条件.     

ω-k-挠自由模与ω-左逼近维数

引进了相对于一个双模ω的ω-k-挠自由模,用左addR ω-逼近刻画了ω-k-挠自由模. 引进了ω-左逼近维数,描述了是k-挠自由模的k-合冲模的形式.     

T-k-挠自由模的扩张闭

本文研究了由T-k-挠自由模所构成的mod-R的完全子模范畴ITk(R)的扩张闭.利用模的级条件和强级条件,获得了ITk(R)扩张团的一个充分条件和一个等价刻画.     

QF-环上有限生成模嵌入自由模的秩数和最小嵌入的算法

一个模嵌入自由模相当于用坐标来表示元素,这在数学上一直有重要意义．理论上, ＱＦ－环上的模都可以嵌入自由模,但没有好的算法,影响了它的应用．本文给出ＱＦ－环上有限生成模的最小嵌入的一种算法和所嵌入自由模的秩数的估计．     

自由模的投射素子模

设R是整环,u是R的素元,F是有限生成自由R-模,M是F的投射子模.本文证明了:若F/M是投射R/(u)-模,或者M是(u)-准素子模,并且F/M是循环模,则当R/(u)既是GE环,又是PF环时,M是自由模.     

格序模的f—复盖

J.Martinez首先利用同调的方法研究了格序结构,讨论了偏序模的张量积.W.Powell和A.Bigard分别在1981年和1973年研究了格序模的自由对象,描述了自由f—模的结构.作者推广并且改进了他们的工作,讨论了格序模的f—张量积.本文讨论格序模的f—模复盖,给出复盖函子,f—张量积函子和嵌入函子的关系.     

K(1,4)-自由的模k泛圈图(英文)

设G是2-连通的K1,4自由图.本文证明了当δ(G)≥k 1时,G是模k泛圈图.这一结果肯定了猜想2,继而也肯定了Thomassen猜想在2-连通图中的正确性.     

ω-k-挠自由模与 ω-左逼近维数

引进了相对于一个双模 ω-的ω-k-挠自由模,用左add_R ω-逼近刻画了ω-k-挠自由模.引进了 ω-左逼近维数,描述了是k-挠自由模的k-合冲模的形式.     

一种模和两个关于多项式的新定理

定义一种秩为n的自由Z -模 ,藉此证明一个关于本原多项式的定理和一个关于用多项式表示素数的定理。     

Koszul Bicomplexes and Generalized Koszul Complexes in Projective Dimension One

We describe Koszul type complexes associated with a linear map from any module to a free module, and vice versa with a linear map from a free module to an arbitrary module, generalizing the classical Koszul complexes. Given a short complex of finite free modules, we assemble these complexes to what we call Koszul bicomplexes. They are used in order to investigate the homology of the Koszul complexes in projective dimension one. As in the case of the classical Koszul complexes, this homology turns out to be grade sensitive. In a special setup, we obtain necessary conditions for a map of free modules to be lengthened to a short complex of free modules.     

Left counital Hopf algebras on free Nijenhuis algebras

Factorization in algebra is an important problem. In this paper, we first obtain a unique factorization in free Nijenhuis algebras. By using of this unique factorization, we then define a coproduct and a left counital bialgebraic structure on a free Nijenhuis algebra. Finally, we prove that this left counital bialgebra is connected and hence obtain a left counital Hopf algebra on a free Nijenhuis algebra.     

Projective limits of nilpotent Hall groups

By analogy with the notion of a pronilpotent W-group, we define the notion of a pronilpotent Lie algebra and establish a one-to-one correspondence between pronilpotent W-groups and pronilpotent Lie algebras in the case where W is a field of zero characteristic; also, we establish a connection between free and projective groups of a given manifold. We prove that, for some manifolds, free and projective groups coincide; we investigate conditions under which a subgroup is free in an absolutely free pronilpotent W-group. In the class of pronilpotent groups, we introduce and discuss the notion of a free product; we construct an example which shows that an analog of the Kurosh theorem on subgroups of a free product does not hold even for finitely generated subgroups. A series of results stated in this paper was announced in [35–38]. __________ Translated from Sovremennaya Matematika i Ee Prilozheniya (Contemporary Mathematics and Its Applications), Vol. 49, Algebra and Geometry, 2007.     

Test elements of direct sums and free products of free Lie algebras

We give a characterization of test elements of a direct sum of free Lie algebras in terms of test elements of the factors. In addition, we construct certain types of test elements and we prove that in a free product of free Lie algebras, product of the homogeneous test elements of the factors is also a test element.     

Free and cofree Hopf algebras

We first prove that a graded, connected, free and cofree Hopf algebra is always self-dual. Then, we prove that two graded, connected, free and cofree Hopf algebras are isomorphic if and only if they have the same Poincaré–Hilbert formal series. If the characteristic of the base field is zero, we prove that the Lie algebra of the primitive elements of such an object is free, and we deduce a characterization of the formal series of free and cofree Hopf algebras by a condition of growth of the coefficients. We finally show that two graded, connected, free and cofree Hopf algebras are isomorphic as (nongraded) Hopf algebras if and only if the Lie algebras of their primitive elements have the same number of generators.     

Free Subordination and Belinschi–Nica Semigroup

We realize the Belinschi–Nica semigroup of homomorphisms as a free multiplicative subordination. This realization allows to define more general semigroups of homomorphisms with respect to free multiplicative convolution. For these semigroups we show that a differential equation holds, generalizing the complex Burgers equation. We give examples of free multiplicative subordination and find a relation to the Markov–Krein transform, Boolean stable laws and monotone stable laws. A similar idea works for additive subordination, and in particular we study the free additive subordination associated to the Cauchy distribution and show that it is a homomorphism with respect to monotone, Boolean and free additive convolutions.     

Line graphs of multigraphs and Hamilton‐connectedness of claw‐free graphs

We introduce a closure concept that turns a claw‐free graph into the line graph of a multigraph while preserving its (non‐)Hamilton‐connectedness. As an application, we show that every 7‐connected claw‐free graph is Hamilton‐connected, and we show that the well‐known conjecture by Matthews and Sumner (every 4‐connected claw‐free graph is hamiltonian) is equivalent with the statement that every 4‐connected claw‐free graph is Hamilton‐connected. Finally, we show a natural way to avoid the non‐uniqueness of a preimage of a line graph of a multigraph, and we prove that the closure operation is, in a sense, best possible. © 2010 Wiley Periodicals, Inc. J Graph Theory 66:152‐173, 2011     

Free martingale polynomials

In this paper we investigate the properties of free Sheffer systems, which are certain families of martingale polynomials with respect to the free Lévy processes. First, we classify such families that consist of orthogonal polynomials; these are the free analogs of the Meixner systems. Next, we show that the fluctuations around free convolution semigroups have as principal directions the polynomials whose derivatives are martingale polynomials. Finally, we indicate how Rota's finite operator calculus can be modified for the free context.     

Free and free abelian Euler-Satake characteristics of nonorientable 2-orbifolds

We compute the Γ-sectors and Γ-Euler-Satake characteristic of a closed, effective 2-dimensional orbifold Q where Γ is a free or free abelian group. Using this information, we determine a family of orbifolds such that the complete collection of Γ-Euler-Satake characteristics associated to free and free abelian groups determines the number and type of singular points of Q as well as the Euler characteristic of the underlying space. Additionally, we show that any collection of these groups whose Euler-Satake characteristics determine this information contains both free and free abelian groups of arbitrarily large rank. It follows that the collection of Euler-Satake characteristics associated to free and free abelian groups constitute a finer orbifold invariant than the collection of Euler-Satake characteristics associated to free groups or free abelian groups alone.     

Smooth zero-contact-angle solutions to a thin-film equation around the steady state

In the simplest case of a linearly degenerate mobility, we view the thin-film equation as a classical free boundary problem. Our focus is on the regularity of solutions and of their free boundary in the “complete wetting” regime, which prescribes zero slope at the free boundary. In order to rule out of the analysis possible changes in the topology of the positivity set, we zoom into the free boundary by looking at perturbations of the stationary solution. Our strategy is based on a priori energy-type estimates which provide “minimal” conditions on the initial datum under which a unique global solution exists. In fact, this solution turns out to be smooth for positive times and to converge to the stationary solution for large times. As a consequence, we obtain smoothness and large-time behavior of the free boundary.