在具有终对象的范畴内的正合列

本文对于具有终对象的范畴定义了四个一般正合列．在Ａｂｅｌ范畴同调代数里，对于具有零对象的任何范畴四个一般正合列与通常的正合列相同     

n-予加法范畴中的弱上积与极限

在Abel范畴的同调代数中,双积和环模的正向系统的正向极限都是重要的基本概念。在那里,由于Abel范畴具有零对象这些概念的讨论就比较简单。本文给出这些概念在n-予加法范畴中的一种推广,我们的困难在于n-予加法范畴只具有终对象。本文的结果表明在n-予加法范畴中这些概念的讨论可以不使用零对象,另一方面也给出在Abel范畴场合中讨论极限时使用零对象的实质的一个解剖。     

Clean-正合和Clean-导出范畴

在交换环R上,引入了Clean-正合以及Clean-导出范畴的概念,分别给出了Clean-短正合列和Clean-正合复形的等价刻画,研究了Clean-导出范畴的性质.特别地,证明了有界Clean-导出范畴可以实现为特殊的同伦范畴.     

L-S-系中的正合列

经典模论中,正合列是研究函子问题的基本工具。在半群S-系理论中,正合列对函子的研究同样起着重要作用。用类似L-模中的方法,给出L-S-系及其正合列的定义,得到已知序列正合的一个必要条。另外,还定义L-S-系中两个短正合列之间的弱同构与同构,并得到在一般S-系范畴中短正合列μ1→μ1Цμ2→μ2弱同构于短正合列μ1→η→μ2的充分条件。     

Yoneda 范畴与线性拓扑空间

<正> 我们为了今后的需要想弄清拓扑代数上的拓扑模构成什么性质的范畴,以及在这种范畴上是否能建立同调代数的基本函子.[8]中讨论了在拓扑模范畴上建立 E_xt~n 与 Torn的问题,但他使用的是相对范畴,要求正合序列(?)-分裂,还有些数学工作者在讨论 Banach模时(例见[12],[13])也要加上类似的条件.但这种条件似乎不太自然.Palamodor 在[15]中引入了半 abel 范畴,但单靠半 abel 范畴本身的结构不足以得到 E_xt~n 函子,必须     

L-fuzzy模范畴中张量函子的正合性

研究了L-fuzzy模范畴中张量函子的正合性,给出平坦L-fuzzy模的概念,讨论了张量函子的正合性与L-fuzzy模的平坦性之间的关系。     

左三角范畴的局部化

本文通过左挠对给出左三角范畴的局部化,证明了左三角范畴的局部化范畴仍然是左三角范畴,并证明了左三角范畴的正合列通过稳定化函子可以导出三角范畴正合列.     

范畴MΔ中的正合列

本文研究域上矩阵给出的范畴,给出了正合性的等价刻画,提出了将正合列理论应用于矩阵论的途径．     

范畴_Δ中的正合列

本文研究域上矩阵给出的范畴,给出了正合性的等价刻画,提出了将正合列理论应用于矩阵论的途径．     

拉回正合范畴中小子对象的探讨

拉回正合范畴是Abelian范畴的真正推广,是界在正合范畴与Abelian范畴之间的一类范畴.本文利用拉回-推出,引进拉回正合范畴的小子对象概念,并给出小子对象相关的性质以及等价条件.     

Algebra retracts and Poincaré-series

Let RA be a local inclusion of noetherian local rings. Assume that R is an algebra retract of A with the local retraction mapping p:AR. Let M be an R-module of finite type. Considering M as A-module via p we get P _M ^A =P _R ^A P _M ^R (Th. 1), where P _N ^S denotes the Poincaréseries of an S-module N. This result is used to give a simple proof of Th. 1 in [2], Also an application to fibre products of rings is given (Th. 2), generalizing slightly a result due to A. Dress and H. Krämer, see [1].     

Equivalences of higher derived brackets

This note elaborates on Th. Voronov’s construction [Th. Voronov, Higher derived brackets and homotopy algebras, J. Pure Appl. Algebra 202 (1-3) (2005) 133-153; Th. Voronov, Higher derived brackets for arbitrary derivations, Travaux Math. XVI (2005) 163-186] of L_∞-structures via higher derived brackets with a Maurer-Cartan element. It is shown that gauge equivalent Maurer-Cartan elements induce L_∞-isomorphic structures. Applications in symplectic, Poisson and Dirac geometry are discussed.     

An integral representation of solutions and the problem of coupling factors for a linear differential equation

The equation ²–(³+a ₂²+a ₁+a ₀)=0, which is encountered in problems of mechanics, is considered in the work. It has two singular points: a regular singular point at zero and an irregular singular point at infinity. A fundamental family of solutions (f.f.s.) can be constructed in the form of integrals of Mellin-Barns type where the integrand satisfies a linear difference equation with polynomial coefficients. On the basis of this representation a f.f.s. is constructed in a neighborhood of zero, and its asymptotics at infinity is found. The coefficients of this asymptotics (the coupling factors) can be represented in the form of analytic expressions containing certain solutions of the difference equation adjoint to the difference equation previously mentioned. In contrast to previous works of the author, the general case of the initial equation is investigated.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova AN SSSR, Vol. 140, pp. 88–104, 1984.     

Sulla completezza e sulla categoricità della teoria delleW-algebre semplici

Riassunto SeW è un'algebra funzionalmente completa si dimostra che le algebre semplici e non degeneri di Var (W) sono tutti e soli i modelli di Th(W); inoltre si dimostra che se card(W=ℵ₀ Th (W) è categorica in ℵ₀, mentre esistono modelli non isomorfi di cardinalità . Se card(W)>ℵ₀ si danno alcuni risultati particolari sulla non categoricità in alcuni cardinali maggiori o uguali a card (W).

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Summary LetW be a functionally complete algebra. We proof that simple and non trivial algebras of variety generated byW are all and only the models of Th (W). Let card(W)=ℵ₀; the we proof Th (W) is ℵ₀-categorical, while there exist not isomorphic models with cardinality . Let card(W)>ℵ₀; then we have some particular results which prove that Th (W) is not α-categorical for some α≥card (W).

     

Nonlocal problems for the equations of Kelvin-Voight fluids and their ɛ-approximations in classes of smooth functions

Existence theorems are proved for the solutions of the first and second initial boundary-value problems for the equations of Kelvin-Voight fluids and for the penalized equations of Kelvin-Voight fluids in the smoothness classes W _∞ ^r (ℝ⁺;W ₂ ^2+k (Ω)), W ₂ ^r (ℝ⁺;W ₂ ^2+k (Ω)) and S ₂ ^r (ℝ⁺;W ₂ ^2+k (Ω)) (r=1,2; k=0,1,2, …) under the condition that the right-hand sides f(x,t) belong to the classes W _∞ ^r-1 (ℝ⁺;W ₂ ^k (Ω)), W ₂ ^r-1 (ℝ⁺;W ₂ ^k (Ω)) and S ₂ ^r-1 (ℝ⁺;W ₂ ^k (Ω)), respectively, and for the solutions of the first and second T-periodic boundary-value problems for the same equations in the smoothness classes W _∞ ^r−1 (ℝ; W ₂ ^2+k (Ω)) and W ₂ ^r−1 (0, T; W ₂ ^2+k (Ω)) (r=1,2, k=0,1,2…) under the condition that f(x,t) are T-periodic and belong to the spaces W _∞ ^r−1 (ℝ⁺; W ₂ ^k (Ω)) and W ₂ ^r−1 (0,T; W ₂ ^k (Ω)), respectively. It is shown that as ɛ→0, the smooth solutions {v^ɛ} of the perturbed initial boundary-value and T-periodic boundary-value problems for the penalized equations of Kelvin-Voight fluids converge to the corresponding smooth solutions (v,p) of the initial boundary-value and T-periodic boundary-value problems for the equations of Kelvin-Voight fluids. Bibliography: 27 titles. Translated fromZapiski Nauchnykh Seminarov POMI, Vol. 230, 1995, pp. 214–242. Translated by T. N. Surkova.     

由分数次导数所确定的L2(T)中的一元周期函数类在Lq(T)中的相对宽度

作者研究了相对宽度K_n(W₂^α(T), MW₂^β(T), L₂(T)), T=[0,2π], 确定了使等式K_n(W₂^α(T), MW₂^β(T), L₂(T))=d_n(W₂^α(T), L₂(T))成立的最小M值, 得到了相对宽度K_n(W₂^α(T), W₂^α(T), L_q(T))的渐近阶, 其中α≥β>0, 1≤q≤∞, K_n(., ., L_q(T)) 和 d_n(., L_q(T))分别表示Kolmogorov意义下L_q(T)尺度下的相对宽度和宽度, MW_p^α(T), 1≤ p≤∞, 表示有如下卷积表达式的2π 周期函数类, f(t)=c+(B_α* g)(t),c∈ R, B_α*g 表示 B_α 和g 的卷积, g∈L_p(T) 满足∫₀^2πg(τ)dτ=0 和||g||_p≤M, B_α∈ L₁(T) 有如下Fourier展开: B_α(t)=1/2π∑' _{k∈ Z}(ik)^-αe^ikt,∑^'表示去掉 k=0的项.     

Smoothk-gonal curves with another fixed pencil

Let X be a smooth curve of genus g with two pencils, sayg _k ¹ andg _m ¹ . Here we show that, in general, dim|rg _k ¹ +ug _m ¹ | has the expected dimension and construct examples in which dim |rg _k ¹ +ug _m ¹ | has a prescribed value.     

Best N Term Approximation Spaces for Tensor Product Wavelet Bases

We consider best N term approximation using anisotropic tensor product wavelet bases ("sparse grids"). We introduce a tensor product structure ⊗_q on certain quasi-Banach spaces. We prove that the approximation spaces A^α_q(L₂) and A^α_q(H¹) equal tensor products of Besov spaces B^α_q(L_q), e.g., A^α_q(L₂([0,1]^d)) = B^α_q(L_q([0,1])) ⊗_q · ⊗_q B^α_{q · ·}(L_q([0,1])). Solutions to elliptic partial differential equations on polygonal/polyhedral domains belong to these new scales of Besov spaces.     

行列式detVn-(x1,...,xn)的准确值及其应用

本文给出行列式Ｖ_n^-(x₁,...,x_n)的准确值，它是通常的Ｖａｎｄｅｒｍｏｄｅ行列式计算公式的推广，以及它在理论上的一些重要应用．     

广义逆多项式模的Attached素理想

设R是有单位元1的结合环,(S,≤)是严格全序Artin幺半群,M_R是右R-模,Att(M_R)与Att([M~(S,≤)]_([[R~(S,≤)]]))分别表示模M_R与广义逆多项式模[M~(S,≤)]_([[R~(S,≤)]])的所有Attached素理想组成的集合.该文主要讨论了广义幂级数环[[R~(S;≤)]]广义逆多项式模[[R~(S;≤)]]的Attached素理想的相关性质,证明了在一定条件下,有Att([M~(S,≤)]_([[R~(S,≤)]])={[[PR~(S;≤)]]P∈Att(M_R)}.这一结论表明广义逆多项式模([M~(S,≤)]_([[R~(S,≤)]])的Attached素理想在一定条件下可以用模M_R的Attached素理想来刻画,推广了Annin S在文献[1]中关于斜多项式环上逆多项式模的Attached素理想的相关结论.