E1类中多项式和有理函数的最佳逼近

In this paper we obtain some estimations of the degree of the best approximation in E¹ space of functions by polynomials and rational functions with preas-signed poles, in which D is an Альпер region, its boundary p satisfies the condition ∫₀(j(u))/u|lnu|du<∞, where j(u) is the continuous modulus of the angle between the tangent of Γ and the positive real axis as the function of the arc length of Γ.     

On the Radius of Analyticity of Solutions to 3D Navier-Stokes System with Initial Data in Lp

Given initial data u₀ ∈ L^p(R³) for some p in[3, 18/5[, the auhtors ?rst prove that 3D incompressible Navier-Stokes system has a unique solution u = uL+v with uL def = et^?u0 and v ∈ e L^∞([0, T]; ˙ H^{5/2 ? 6/p} ) ∩ L¹(]0, T[; ˙H^{9/2 ? 6/p} ) for some positive time T. Then they derive an explicit lower bound for the radius of space analyticity of v, which in particular extends the corresponding results in [Chemin, J.-Y., Gallagher, I. and Zhang, P., On the radius of analyticity of solutions to semi-linear parabolic system, Math. Res. Lett., 27, 2020, 1631– 1643, Herbst, I. and Skibsted, E., Analyticity estimates for the Navier-Stokes equations, Adv. in Math., 228, 2011, 1990–2033] with initial data in ˙H^s(R³) for s∈[1/2,3/2[.     

关于具有多项式约束的I-环

In this paper, it is shown that an l-prime lattice-ordered ring in which the square of every element is positive must be a domain provided it has non-zero f-elements and be an l-domain provided it has a left (right) identity ele-ment or a central idempotent element .More generally,the same conclusion follows if the condition a²≥0 is replaced by p(a)≥0 or f(a,b)≥0 for suitable polyno-mials p(x) and f(x, y) . It is also shown that an l-algebra is an f-algebra provided it is archimedean, contains an f-element e>0 with r₁(e)=0, and satifies a polynomial identity p(x)≥0 or f(x,y)≥0 (for suitable f(x,y)).     

类2的常数联络黎曼空间

A non-flat Riemannian space V_n is called Riemannian space with constant connection if its Christoffel symbols of the second kind are constant in some coordinate system {xⁱ}. Following G. Vranceanu [3], a Riemannian space V_n with constant connection is said to be of genus p, if the components of the fundamental tensor in the coordinate system {x^{i/sup>} can be written in the form g_ij=c_ijat_a(a=1,…,p) where c_ija are constant, and p is least.In this paper we prove the following}     

Multiplicity of Solutions of the Weighted p-Laplacian with Isolated Singularity and Diffusion Suppressed by Convection

In this paper, the authors study the multiplicity of solutions to the weighted p-Laplacian with isolated singularity and di?usion suppressed by convection ?div(|x|^α|?u|^p?2?u) + λ 1/|x|^β |?u|^p?2?u · x = |x|^γg(|x|) in B \ {0} subject to nonlinear Robin boundary value condition |x|^α|?u|^p?2?u · ?n = A ? ρu on ?B,where λ > 0, B ? R^N(N ≥ 2) is the unit ball centered at the origin, α > 0, p > 1, β ∈ R, γ > ?N, g ∈ C([0,1]) with g(0) > 0, A ∈ R, ρ > 0 and ?n is the unit outward normal. The same problem with di?usion promoted by convection, namely λ ≤ 0, has already been discussed by the last two authors (Song-Yin (2012)), where the existence, nonexistence and classi?cation of singularities for solutions are presented. Completely di?erent from [Song, H. J. and Yin, J. X., Removable isolated singularities of solutions to the weighted p-Laplacian with singular convection, Math. Meth. Appl. Sci., 35, 2012, 1089–1100], in the present case λ > 0, namely the di?usion is suppressed by the convection, non-singular solutions are not only existent but also may be in?nite which vary according only to the values of solutions at the isolated singular point. At the same time, the singular solutions may exist only if the di?usion dominates the convection.     

树的罗马控制数和控制数

A Roman dominating function on a graph G = (V, E) is a function f : V→{0, 1, 2} satisfying the condition that every vertex u for which f(u) = 0 is adjacent to at least one vertex v for which f(v) - 2. The weight of a Roman dominating function is the value (?). The minimum weight of a Roman dominating function on a graph G, denoted byγR(G), is called the Roman dominating number of G. In this paper, we will characterize a tree T withγR(T) =γ(T) 3.     

CONVERGENCE OF AN ITERATION METHOD WITHOUT DERIVATIVE

In this paper, we give a convergence theorem and error estimates for an iteration method under new Kantorovitch-Ostrowski type condition using the information of higher derivatives at initial points. Compared with the corresponding study in [3],the convergence determination is established under one global condition, instead of two , on the function.     

正态分布方差SPRT的maxE(n)

In this paper the explicit formulae of ASN's maximum are derived for SPRT under normal distribution N(μ₀,σ²), where σ² is an unknown parameter. And under the same condition we have obtained the size of sample of single samp-ling inspection plan.     

Quenching Phenomenon for a Parabolic MEMS Equation

This paper deals with the electrostatic MEMS-device parabolic equation u_t-?u =λf(x)/(1-u)~p in a bounded domain ? of R~N,with Dirichlet boundary condition,an initial condition u0(x) ∈ [0,1) and a nonnegative profile f,where λ 0,p 1.The study is motivated by a simplified micro-electromechanical system(MEMS for short) device model.In this paper,the author first gives an asymptotic behavior of the quenching time T*for the solution u to the parabolic problem with zero initial data.Secondly,the author investigates when the solution u will quench,with general λ,u0(x).Finally,a global existence in the MEMS modeling is shown.     

关于Ahuja的一个结果

In [1], O. P. Ahuja established the following result: If F is an element of R_n(α)for n≥0 and 0≤α<1, F(z)=(c+1)/(z~c)integral from 0 to z f(t)t~(c-1)dt with |z|<1,Rec≥-α, and 0≤β<1. then the function f is an element of R_n(β) for |z|相似文献   

一致网格上二次样条插值及其在积分中的应用（英）

In this paper an error estimate is derived, if λ∈[0, 1], for tile lacunaryquartic C²-spline interpolant which interpolates the first derivative of a given smooth function at the mesh points and as well as its second derivative at an arbitrary interior point between consecutive knots, if the mesh is uniform. Moreover, all application to quadratures is also presented.     

6q+1级2—传递置换群,q为素数

In [ 3 ] M. D. Atkinson conjectured that if G is a doubly transitive but not doubly primitive permutation group on Ω, then G is of one of the following four types: i) Metacyclic groups of prime degree p and of order p(p -1); ii) Groups of degree 2^p and of order 2^p(2^p-1)or 2^p(2^p-l)p for some prime p;iii)Gr-oups of automorphisms of a block design with λ=1; iv) Sz(q)≤G≤Aut(Sz(g)).In this paper we proved this conjecture in a special case without using the result of classification of finte simple groups, Qur explicit result is as follows: Theorem. Let G be a doubly transitive group on set Ω,where |Ω|=6q+1 and q is a prime, then one of the following holds: i)G is doubly primitive on Ω;ii) G is sharply doubly transitive on Ω; iii) G is a groups of automorphisms of a block design with λ=1.     

The K?hler-Einstein metric for some Hartogs domains over symmetric domains

We study the complete K?hler-Einstein metric of a Hartogs domain built on an irreducible bounded symmetric domain sW, using a power N ^μ of the generic norm of Ω. The generating function of the K?hler-Einstein metric satisfies a complex Monge-Ampère equation with a boundary condition. The domain is in general not homogeneous, but it has a subgroup of automorphisms, the orbits of which are parameterized by X ε [0, 1[. This allows us to reduce the Monge-Ampère equation to an ordinary differential equation with a limit condition. This equation can be explicitly solved for a special value μ₀ of μ. We work out the details for the two exceptional symmetric domains. The special value μ₀ seems also to be significant for the properties of other invariant metrics like the Bergman metric; a conjecture is stated, which is proved for the exceptional domains.     

Stochastic maximum principle for mean-field forward-backward stochastic control system with terminal state constraints

In this paper,we consider an optimal control problem with state constraints,where the control system is described by a mean-field forward-backward stochastic differential equation(MFFBSDE,for short)and the admissible control is mean-field type.Making full use of the backward stochastic differential equation theory,we transform the original control system into an equivalent backward form,i.e.,the equations in the control system are all backward.In addition,Ekeland’s variational principle helps us deal with the state constraints so that we get a stochastic maximum principle which characterizes the necessary condition of the optimal control.We also study a stochastic linear quadratic control problem with state constraints.     

关于解析函数的一个不等式

Let P(Z) = 1 + P₁Z + P₂Z² +…be an analytic function in the unit disc D. In thispaper, we determine the value of φ(α,β) for which Re[P(Z) + αZP′(Z)] > β,Z ∈ D,α > 0,β < 1 implies that Re{P(Z)} >φ(α,β) for all Z ∈ D, and this result is sharp. Some of its interesting consequences are also given. In addition, we give a new univalence criterion.     

按有理函数系展开函数成Fourier级数

In this paper we give some orthogonal system of rational functions on the unit circumference; We obtained the Riemann Lemma and some tests of convergence of Fourier series for this orthogonal system with the poles {α_k}₀^∞ satisfying some conditions, The conditions we obtained are weaker than those established in [2].     

Long-time Asymptotic Behavior for the Derivative Schr¨odinger Equation with Finite Density Type Initial Data*

In this paper, the authors apply ? steepest descent method to study the Cauchy problem for the derivative nonlinear Schr¨odinger equation with finite density type initial data iq_t + q_xx + i(|q|²q)x = 0,q(x, 0) = q0(x),where lim/x→±∞ q0(x) = q± and |q±| = 1. Based on the spectral analysis of the Lax pair,they express the solution of the derivative Schr¨odinger equation in terms of solutions of a Riemann-Hilbert problem. They compute the long time asymptotic expansion of the solution q(x, t) in different space-time regions. For the region ξ =x/t with |ξ + 2| < 1, the long time asymptotic is given by q(x, t) = T (∞)^?2q^r_Λ(x, t) + O(t^?3/4 ),in which the leading term is N(I) solitons, the second term is a residual error from a ? equation. For the region |ξ + 2| > 1, the long time asymptotic is given by q(x, t) = T (∞)^?2q^r_Λ(x, t) ? t^?1/2 if¹¹ + O(t^?3/4 ),in which the leading term is N(I) solitons, the second t^?1/2 order term is soliton-radiation interactions and the third term is a residual error from a ? equation. These results are verification of the soliton resolution conjecture for the derivative Schr¨odinger equation. In their case of finite density type initial data, the phase function θ(z) is more complicated that in finite mass initial data. Moreover, two triangular decompositions of the jump matrix are used to open jump lines on the whole real axis and imaginary axis, respectively.     

The <Emphasis Type="Italic">p</Emphasis>-rank of Ext<Subscript>ℤ</Subscript>(<Emphasis Type="Italic">G</Emphasis>, ℤ) in certain models of <Emphasis Type="Italic">ZFC</Emphasis>

We prove that if the existence of a supercompact cardinal is consistent with ZFC, then it is consistent with ZFC that the p-rank of Ext _ℤ(G, ℤ) is as large as possible for every prime p and for any torsion-free Abelian group G. Moreover, given an uncountable strong limit cardinal μ of countable cofinality and a partition of Π (the set of primes) into two disjoint subsets Π₀ and Π₁, we show that in some model which is very close to ZFC, there is an almost free Abelian group G of size 2^μ = μ⁺ such that the p-rank of Ext _ℤ(G, ℤ) equals 2^μ = μ⁺ for every p ∈ Π₀ and 0 otherwise, that is, for p ∈ Π₁. Number 874 in Shelah’s list of publications. Supported by the German-Israeli Foundation for Scientific Research & Development project No. I-706-54.6/2001. Supported by a grant from the German Research Foundation DFG. __________ Translated from Algebra i Logika, Vol. 46, No. 3, pp. 369–397, May–June, 2007.     

A REPRESENTATION FORMULA RELATED TO SCHROEDINGER OPERATORS

Schroedinger operator is a central subject in the mathematical study of quantum mechanics.Consider the SchrSdinger operator H=-Δ V on R, where Δ=d^2/dx^2 and the potential function V is real valued. In Fourier analysis, it is well-known that a square integrable function admits an expansion with exponentials as eigenfunctions of-Δ. A natural conjecture is that an L^2 function admits a similar expansion in terms of “eigenfunctions“ of H, a perturbation of the Laplacian (see [7], Ch. XI and the notes), under certain condition on V.     

Harnack inequality and gradient estimate for G-SDEs with degenerate noise

In this paper,the Harnack inequality for G-SDEs with degenerate noise is derived by the method of coupling by change of the measure.Moreover,for any bounded and continuous function f,the gradient estimate∣?P_tf∣≤c(p,t)(Pt|f|p)^1/p,p>1,t>0 is obtained for the associated nonlinear semigroup Pˉt.As an application of the Harnack inequality,we prove the existence of the weak solution to degenerate G-SDEs under some integrable condition.Finally,an example is presented.All of the above results extend the existing ones in the linear expectation setting.