Frontiers of Mathematics in China

ISSN 1673-3452

ISSN 1673-3576(Online)

CN 11-5739/O1

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, Volume 8 Issue 4

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RESEARCH ARTICLE
Neutral stochastic delay partial functional integro-differential equations driven by a fractional Brownian motion
Tomás CARABALLO, Mamadou Abdoul DIOP
Front Math Chin. 2013, 8 (4): 745-760.  
https://doi.org/10.1007/s11464-013-0300-3

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This paper deals with the existence and uniqueness of mild solutions to neutral stochastic delay functional integro-differential equations perturbed by a fractional Brownian motion BH, with Hurst parameter H∈ (1/2, 1). We use the theory of resolvent operators developed by R. Grimmer to show the existence of mild solutions. An example is provided to illustrate the results of this work.

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Approximations for modulus of gradients and their applications to neighborhood filters
Yan CHEN, Zhuangji WANG, Kewei ZHANG
Front Math Chin. 2013, 8 (4): 761-782.  
https://doi.org/10.1007/s11464-013-0297-7

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We define an integral approximation for the modulus of the gradient |?u(x)| for functions f:Ω??n? by modifying a classical result due to Calderon and Zygmund. Our integral approximations are more stable than the pointwise defined derivatives when applied to numerical differentiation for discrete data. We apply our results to design and analyse neighborhood filters. These filters correspond to well-behaved nonlinear heat equations with the conductivity decreasing with respect to the modulus of gradient |?u(x)|. We also show some numerical experiments and evaluate the effectiveness of our filters.

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Double Hilbert transform on D(?2)
Xiaona CUI, Rui WANG, Dunyan YAN
Front Math Chin. 2013, 8 (4): 783-799.  
https://doi.org/10.1007/s11464-013-0269-y

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We introduce a space DHH=D(?2)H2H1D(?2), where D(?2) is the testing function space whose functions are infinitely differentiable and have bounded support, and H2H1D(?2) is the space the double Hilbert transform acting on the testing function space.We prove that the double Hilbert transform is a homeomorphism from DHH onto itself.

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Properties of Hamilton cycles of circuit graphs of matroids
Hao FAN, Guizhen LIU
Front Math Chin. 2013, 8 (4): 801-809.  
https://doi.org/10.1007/s11464-013-0240-y

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Let G be a circuit graph of a connected matroid. P. Li and G. Liu [Comput. Math. Appl., 2008, 55: 654-659] proved that G has a Hamilton cycle including e and another Hamilton cycle excluding e for any edge eof Gif Ghas at least four vertices. This paper proves that G has a Hamilton cycle including e and excluding e' for any two edges e and e'of G if G has at least five vertices. This result is best possible in some sense. An open problem is proposed in the end of this paper.

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Existence and uniqueness result for multidimensional BSDEs with generators of Osgood type
Shengjun FAN, Long JIANG, Matt DAVISON
Front Math Chin. 2013, 8 (4): 811-824.  
https://doi.org/10.1007/s11464-013-0298-6

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This paper is interested in solving a multidimensional backward stochastic differential equation (BSDE) whose generator satisfies the Osgood condition in y and the Lipschitz condition in z. We establish an existence and uniqueness result of solutions for this kind of BSDEs, which generalizes some known results.

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Time discontinuous Galerkin space-time finite element method for nonlinear Sobolev equations
Siriguleng HE, Hong LI, Yang LIU
Front Math Chin. 2013, 8 (4): 825-836.  
https://doi.org/10.1007/s11464-013-0307-9

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This article presents a complete discretization of a nonlinear Sobolev equation using space-time discontinuous Galerkin method that is discontinuous in time and continuous in space. The scheme is formulated by introducing the equivalent integral equation of the primal equation. The proposed scheme does not explicitly include the jump terms in time, which represent the discontinuity characteristics of approximate solution. And then the complexity of the theoretical analysis is reduced. The existence and uniqueness of the approximate solution and the stability of the scheme are proved. The optimalorder error estimates in L2(H1) and L2(L2) norms are derived. These estimates are valid under weak restrictions on the space-time mesh, namely, without the condition knch2, which is necessary in traditional space-time discontinuous Galerkin methods. Numerical experiments are presented to verify the theoretical results.

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Convergence and stability of two-level penalty mixed finite element method for stationary Navier-Stokes equations
Pengzhan HUANG, Yinnian HE, Xinlong FENG
Front Math Chin. 2013, 8 (4): 837-854.  
https://doi.org/10.1007/s11464-013-0257-2

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The two-level penalty mixed finite element method for the stationary Navier-Stokes equations based on Taylor-Hood element is considered in this paper. Two algorithms are proposed and analyzed. Moreover, the optimal stability analysis and error estimate for these two algorithms are provided. Finally, the numerical tests confirm the theoretical results of the presented algorithms.

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On weakly s-permutably embedded subgroups of finite groups (II)
Yujian HUANG, Yangming LI, Shouhong QIAO
Front Math Chin. 2013, 8 (4): 855-867.  
https://doi.org/10.1007/s11464-013-0287-9

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Suppose that G is a finite group and H is a subgroup of G. H is said to be s-permutably embedded in G if for each prime p dividing |H|, a Sylow p-subgroup of H is also a Sylow p-subgroup of some s-permutable subgroup of G; H is called weakly s-permutably embedded in G if there are a subnormal subgroup T of G and an s-permutably embedded subgroup Hse of G contained in H such that G = HT and HTHse. In this paper, we continue the work of [Comm. Algebra, 2009, 37: 1086-1097] to study the influence of the weakly s-permutably embedded subgroups on the structure of finite groups, and we extend some recent results.

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Constructions of optimal variable-weight OOCs via quadratic residues
Yan LIU, Dianhua WU
Front Math Chin. 2013, 8 (4): 869-890.  
https://doi.org/10.1007/s11464-012-0220-7

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Variable-weight optical orthogonal code (OOC) was introduced by G. C. Yang [IEEE Trans. Commun., 1996, 44: 47-55] for multimedia optical CDMA systems with multiple quality of service (QoS) requirements. In this paper, seven new infinite classes of optimal (v, {3, 4, 6}, 1,Q)-OOCs are constructed.

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Growth of certain harmonic functions in an n-dimensional cone
Lei QIAO, Guantie DENG
Front Math Chin. 2013, 8 (4): 891-905.  
https://doi.org/10.1007/s11464-012-0253-y

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We give the growth properties of harmonic functions at infinity in a cone, which generalize the results obtained by Siegel-Talvila.

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Herz type Besov and Triebel-Lizorkin spaces with variable exponent
Chune SHI, Jingshi XU
Front Math Chin. 2013, 8 (4): 907-921.  
https://doi.org/10.1007/s11464-012-0248-8

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The Herz type Besov and Triebel-Lizorkin spaces with variable exponent are introduced. Then characterizations of these new spaces by maximal functions are given.

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Zero density of L-functions related to Maass forms
Hengcai TANG
Front Math Chin. 2013, 8 (4): 923-932.  
https://doi.org/10.1007/s11464-013-0303-0

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Let f(z) be a Hecke-Maass cusp form for SL2(?), and let L(s, f) be the corresponding automorphic L-function associated to f. For sufficiently large T, let N(σ, T ) be the number of zeros ρ =β +iγ of L(s, f) with |γ|≤T, βσ, the zeros being counted according to multiplicity. In this paper, we get that for 3/4≤σ≤1-?, there exists a constant C = C(?) such that N(σ,T)?T2(1-σ)/σ(log?T)C, which improves the previous results.

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Generalized Jacobi-Gauss-Lobatto interpolation
Zhengsu WAN, Benyu GUO, Chengjian ZHANG
Front Math Chin. 2013, 8 (4): 933-960.  
https://doi.org/10.1007/s11464-013-0271-4

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We introduce the generalized Jacobi-Gauss-Lobatto interpolation involving the values of functions and their derivatives at the endpoints, which play important roles in the Jacobi pseudospectral methods for high order problems. We establish some results on these interpolations in non-uniformly weighted Sobolev spaces, which serve as the basic tools in analysis of numerical quadratures and various numerical methods of differential and integral equations.

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Boundedness of Calderón-Zygmund operators with finite non-doubling measures
Dachun YANG, Dongyong YANG
Front Math Chin. 2013, 8 (4): 961-971.  
https://doi.org/10.1007/s11464-013-0210-4

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Let μ be a nonnegative Radon measure on ?d which satisfies the polynomial growth condition that there exist positive constants C0 and n ∈ (0, d] such that, for all x?d and r>0, μ(B(x, r))≤C0rn, where B(x, r) denotes the open ball centered at x and having radius r. In this paper, we show that, if μ(?d)<∞, then the boundedness of a Calderón-Zygmund operator T on L2(μ) is equivalent to that of T from the localized atomic Hardy space h1(μ) to L1,∞(μ) or from h1(μ) to L1(μ).

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Derivation algebra and automorphism group of generalized topological N = 2 superconformal algebra
Hengyun YANG, Yafeng YU, Tingfu YAO
Front Math Chin. 2013, 8 (4): 973-986.  
https://doi.org/10.1007/s11464-013-0306-x

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We determine the derivation algebra and the automorphism group of the generalized topological N = 2 superconformal algebra.

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Hereditarily covering properties of inverse sequence limits
Bin ZHAO, Aili SONG, Jing WEI
Front Math Chin. 2013, 8 (4): 987-997.  
https://doi.org/10.1007/s11464-013-0277-y

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Let {Xi, πki,ω} be an inverse sequence and X = lim?{Xi,πki,ω}. If each Xi is hereditarily (resp. metaLindel?f, σ-metaLindel?f, σ-orthocompact, weakly suborthocompact, δθ-refinable, weakly θ-refinable, weakly δθ-refinable), then so is X.

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16 articles