Generalized (f,U s,u t , λ s t )-structures

iauliai Pedagogical Institute, P. Viinskio str. 25, 5419 iauliai, Lithuania. Translated from Lietuvos Matematikos Rinkinys, Vol. 33, No. 2, pp. 135–141, April–June, 1993.     

(s,t,d)-bi-Koszul代数

本文关注具有non-pure分解的1次生成正分次代数,主要讨论作为bi-Koszul代数的推广的一类新的代数(s,t,d)-bi-Koszul代数.用两个具有pure分解的周期代数可以获得(s,t,d)-bi-Koszul代数.本文讨论了(s,t,d)-bi-Koszul代数的Koszul对偶的生成性,在此基础上,提出了强(s,t,d)-bi-Koszul代数的概念并且进一步讨论了它们的同调性质.     

Finite Dimensional Lie Superalgebras W(m,n,t) and S(m,n,t) of Cartan Type

设Ｌ＝Ｗ或Ｓ，Ｆ是特征数大于２的域．本文证明了Ｆ上的有限维单李超代数Ｌ（ｍ，ｎ，ｔ）的自然滤过是不变的．进而得出了Ｌ（ｍ，ｎ，ｔ）与Ｌ（ｍ′，ｎ′，ｔ′）同构的充要条件是ｍ＝ｍ′，ｎ＝ｎ′和ｔｉ＝τ（ｔ′ｉ），ｉ＝１，２，…，ｍ，这里τ是｛１，２，…，ｍ｝的一个置换．     

Nonexistence of Complete (st−t/s)-Arcs in Generalized Quadrangles of Order (s, t), I

Let $\text{S}$ be a finite generalized quadrangle (GQ) of order (s, t), s≠1≠t. A k-arc $\text{K}$ is a set of k mutually non-collinear points. For any k-arc of $\text{S}$ we have k⩽st+1; if k=st+1, then $\text{K}$ is an ovoid of $\text{S}$. A k-arc is complete if it is not contained in a k′-arc with k′>k. In S. E. Payne and J. A. Thas, Finite Generalized Quadrangles, Pitman, Boston, 1984, it is proved that an (st−m)-arc, where −1⩽m<t/s, is always contained in a uniquely defined ovoid, hence it is a natural question to ask whether or not complete (st−t/s)-arcs exist. In this note, we prove that the classical GQ H(4, q²) has no complete (q⁵−q)-arcs. We also show that a GQ $\text{S}$ of order s with a regular point has no complete (s²−1)-arcs, except when s=2, i.e. $\text{S}$≅$\text{Q}$(4, 2), and in that case there is a unique example. As a by-product there follows that no known GQ of even order s with s>2 can have complete (s²−1)-arcs. Also, we prove that a GQ of order (s, s²), s≠1, cannot have complete (s³−s)-arcs unless s=2, i.e., $\text{S}$≅$\text{Q}$(5, 2), in which case there is a unique example (up to isomorphism).     

Partial t-spreads and group constructible (s,r,μ)-nets

We give a method for constructing (s,r,)-nets out of partial t-spreads. As one consequence, we are able to apply a theorem of Bose and Bush to improve the known upper bound for the number of subspaces in a partial t-spread. Conversely, known existence results for partial t-spreads yield (s,r,)-nets with large replication number r.     

THE STABILITY OF RDDE (?)(t) p_1(t)x(t) q_1(t)x(t) p_2(t)x(t-r(t)) q_2(t)x(t-r(t))=0

In this paper, the author considered the stability of zero solution of linear RDDEx(t) p_1(t)x(t) q_1(t)x(t) p_2(t)x(t-r(t)) q_2(t)x(t-r(t))=0,(1)x(t) p_1(t)x(t) q_1(t)x(t) q_2(t)x(t-r(t))=0 (2)using Liapunov-Razumikhin functional and transformations and obtained some sufficient condi-tions for the stability of Eqs.(1) and (2). These results are suitable both for bounded p_i(t), q_i(t)and r(t).i =1, 2.     

Property (aw) and Weyl’s Theorem

In this note we study the property (aw), a variant of Weyl’s theorem introduced by Berkani and Zariouh, by means of the localized single valued extension property (SVEP). We establish for a bounded linear operator defined on a Banach space several sufficient and necessary conditions for which property (aw) holds. We also relate this property with Weyl’s theorem, a-Weyl’s theorem and property (w). Finally, we show that if T is a-polaroid and either T or T* has SVEP then f(T) satisfies property (aw) for each ${f \in H_1(\sigma(T))}$ .     

方程(t)+p(t)(t)+q(t)x(t)=0的稳定性

本文应用交换技巧以及直接方法研究了二阶线性系统(1)的平凡解的稳定性,得到若干充分条件、必要条件以及充分必要条件,推广了文献[1—8]中的有关结果。     

(r(t)y′)′+a(t)y=F(t,y)解的有界性与零解的稳定性

本文讨论二阶非线性微分方程(r(t)y′)′+a(t)y=F(t,y) (1)解的有界性与零解的稳定性问题,证明在一类简单条件下,(1)的解与线性齐次方程(r(t)y′)′+a(t)y=0 (2)的解具有相同类型的有界性质与稳定性.本文推广了[2,3]的相应工作.在[3]中令g(x(t))=y)(t),则[3]的方程包含于(1)中,且x(t)与y(t)具有相同的渐近性质. 现作如下的基本假设:     

The Existence of a Positive Solution of D α[x(t) − x(0)] = x(t)f(t,x t )

This paper is devoted to the problem of existence of positive solution for a delay differential equation with fractional order. Some sufficient conditions for its existence of positive solution are given. This work was supported in part by the Key Project of the National Nature Science Foundation of China (No. 60534020), the National Nature Science Foundation of China (No. 60474037), and Program for New Century Excellent Talents in University (No. NCET-04-415).     

On Embeddings of AG(tn,k) into AG(t,K) with t≥2, n≥1

Let k and K be commutative fields with dim_kK=2n, n1 and char(k)2, 3. If k satisfies one of the following conditions: (1) k is a finite field and k contains a 3-th root of unity, or (2) K is a cyclic extension of k where k is not 3-closed, and k contains a 2^a3^b-th root of unity, where 6n=2^a3^bc and c is coprime to 2, 3, then there exists an embedding of the tn-dimensional affine space AG(tn,k) into the t-dimensional affine space AG(t,K), for all t2.     

N(t) = N(t) [a(t)-sum from i=1 to n (b_i(t)N~i(t-τ_i(t)))]的周期正解(英文)

用非线性分析的方法讨论了方程N（t）=N（t）[a（t）－bi（t）Ni（t-τ（t））周的周期正待的存在性，所获结果包含或推广了已有的几个结论[2，3]．     

关于$F(p,s)$-Teichmuller空间

在本文中,我们刻画了$F(p,s)$-Teichmuller空间的Bers投影在原点的微分.     

Properties of (θ,s)-continuous functions

Joseph and Kwack [Proc. Amer. Math. Soc. 80 (1980) 341–348] introduced the notion of (θ,s)-continuous functions in order to investigate S-closed spaces due to Thompson [Proc. Amer. Math. Soc. 60 (1976) 335–338]. In this paper, further properties of (θ,s)-continuous functions are obtained and relationships between (θ,s)-continuity, contra-continuity and regular set-connectedness defined by Dontchev et al. [Internat. J. Math. Math. Sci. 19 (1996) 303–310 and elsewhere] are investigated.     

Benford’s law and distribution functions of sequences in (0, 1)

Applying the theory of distribution functions of sequences x _n ∈ [0, 1], n = 1, 2, ..., we find a functional equation for distribution functions of a sequence x _n and show that the satisfaction of this functional equation for a sequence x _n is equivalent to the fact that the sequence x _n to satisfies the strong Benford law. Examples of distribution functions of sequences satisfying the functional equation are given with an application to the strong Benford law in different bases. Several direct consequences from uniform distribution theory are shown for the strong Benford law.     

Hermitean (semi) lattices and Rolf��s lattice

We investigate the indexed Hermitean lattice of type 0 generated by a single element a subject to the relation ${a = a^\amalg \leq b = b^\amalg}$ . Although the lattice is infinite, we are able to recursively describe its subdirectly irreducible factors. We also give necessary and sufficient conditions about indices for this lattice to be finite.