Frontiers of Mathematics in China

ISSN 1673-3452

ISSN 1673-3576(Online)

CN 11-5739/O1

邮发代号 80-964

2019 Impact Factor: 1.03

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2020年, 第15卷 第6期 出版日期:2020-12-15

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The (b; c)-inverse in semigroups and rings with involution
Xiaofeng CHEN, Jianlong CHEN
Frontiers of Mathematics in China. 2020, 15 (6): 1089-1104.  
https://doi.org/10.1007/s11464-020-0880-7

摘要   PDF (280KB)

We first prove that if a is both left (b; c)-invertible and left (c; b)- invertible, then a is both (b; c)-invertible and (c; b)-invertible in a *-monoid, which generalizes the recent result about the inverse along an element by L. Wang and D. Mosić [Linear Multilinear Algebra, Doi.org/10.1080/03081087. 2019.1679073], under the conditions (ab)* = ab and (ac)* = ac: In addition, we consider that ba is (c; b)-invertible, and at the same time ca is (b; c)-invertible under the same conditions, which extend the related results about Moore- Penrose inverses studied by J. Chen, H. Zou, H. Zhu, and P. Patrício [Mediterr J. Math., 2017, 14: 208] to (b; c)-inverses. As applications, we obtain that under condition (a2)* = a2; a is an EP element if and only if a is one-sided core invertible, if and only if a is group invertible.

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Largest signless Laplacian spectral radius of uniform supertrees with diameter and pendent edges (vertices)
Cunxiang DUAN, Ligong WANG, Peng XIAO
Frontiers of Mathematics in China. 2020, 15 (6): 1105-1120.  
https://doi.org/10.1007/s11464-020-0879-0

摘要   PDF (313KB)

Let S(m; d; k) be the set of k-uniform supertrees with m edges and diameter d; and S1(m; d; k) be the k-uniform supertree obtained from a loose path u1; e1; u2; e2,..., ud; ed; ud+1 with length d by attaching md edges at vertex ud/2+1: In this paper, we mainly determine S1(m; d; k) with the largest signless Laplacian spectral radius in S(m; d; k) for 3≤dm –1: We also determine the supertree with the second largest signless Laplacian spectral radius in S(m; 3; k): Furthermore, we determine the unique k-uniform supertree with the largest signless Laplacian spectral radius among all k-uniform supertrees with n vertices and pendent edges (vertices).

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Local regularity properties for 1D mixed nonlinear Schrödinger equations on half-line
Boling GUO, Jun WU
Frontiers of Mathematics in China. 2020, 15 (6): 1121-1142.  
https://doi.org/10.1007/s11464-020-0878-1

摘要   PDF (317KB)

The main purpose of this paper is to consider the initial-boundary value problem for the 1D mixed nonlinear Schrödinger equation ut=iαuxx+βu2ux+γ|u|2ux+i|u|2u on the half-line with inhomogeneous boundary condition. We combine Laplace transform method with restricted norm method to prove the local well-posedness and continuous dependence on initial and boundary data in low regularity Sobolev spaces. Moreover, we show that the nonlinear part of the solution on the half-line is smoother than the initial data.

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Properties of Berwald scalar curvature
Ming LI, Lihong ZHANG
Frontiers of Mathematics in China. 2020, 15 (6): 1143-1153.  
https://doi.org/10.1007/s11464-020-0872-7

摘要   PDF (296KB)

We prove that a Finsler manifold with vanishing Berwald scalar curvature has zero E-curvature. As a consequence, Landsberg manifolds with vanishing Berwald scalar curvature are Berwald manifolds. For (α,β)-metrics on manifold of dimension greater than 2, if the mean Landsberg curvature and the Berwald scalar curvature both vanish, then the Berwald curvature also vanishes.

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Multiple P-cyclic symmetric closed characteristics on compact convex P-cyclic symmetric hypersurfaces in 2n
Hui LIU, Hui ZHANG
Frontiers of Mathematics in China. 2020, 15 (6): 1155-1173.  
https://doi.org/10.1007/s11464-020-0885-2

摘要   PDF (307KB)

Let k>2 be an integer and P be a 2n×2n symplectic orthogonal matrix satisfying Pk = I2n and ker(Pj - I2n) = 0; 1≤j <k: For any compact convex hypersurface 2n with n≥2 which is P-cyclic symmetric, i.e., x implies Px ; we prove that if is (r;R)-pinched with R/r<(2k+2)/k,then there exist at least n geometrically distinct P-cyclic symmetric closed characteristics on for a broad class of matrices P:

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On intervals and sets of hypermatrices (tensors)
Saeed RAHMATI, Mohamed A. TAWHID
Frontiers of Mathematics in China. 2020, 15 (6): 1175-1188.  
https://doi.org/10.1007/s11464-020-0884-3

摘要   PDF (270KB)

Interval hypermatrices (tensors) are introduced and interval α-hypermatrices are uniformly characterized using a finite set of 'extreme' hypermatrices, where α can be strong P, semi-positive, or positive definite, among many others. It is shown that a symmetric interval is an interval (strictly) copositive-hypermatrix if and only if it is an interval (E) E0-hypermatrix. It is also shown that an even-order, symmetric interval is an interval positive (semi-) definite-hypermatrix if and only if it is an interval P (P0)-hypermatrix. Interval hypermatrices are generalized to sets of hyper-matrices, several slice-properties of a set of hypermatrices are introduced and sets of hypermatrices with various slice-properties are uniformly characterized. As a consequence, several slice-properties of a compact, convex set of hyper-matrices are characterized by its extreme points.

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Existence and multiplicity results for nonlinear Schrödinger-Poisson equation with general potential
Yuan SHAN
Frontiers of Mathematics in China. 2020, 15 (6): 1189-1200.  
https://doi.org/10.1007/s11464-020-0881-6

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This paper is concerned with the Schrödinger-Poisson equationΔu+V(x)u+φ(x)u=f(x,u),x3,Δφ=u2,lim|x|+φ(x)=0.

Under certain hypotheses on V and a general spectral assumption, the existence and multiplicity of solutions are obtained via variational methods.

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Flag-transitive 2-υ,5,λ designs with sporadic socle
Jiaxin SHEN, Shenglin ZHOU
Frontiers of Mathematics in China. 2020, 15 (6): 1201-1210.  
https://doi.org/10.1007/s11464-020-0876-3

摘要   PDF (327KB)

We state that the ag-transitive automorphism group of a 2-υ,5,λ design D is primitive of affine type or almost simple type. We also find that there are up to isomorphism 20 2-υ,5,λ designs admitting flag-transitive automorphism groups with socle of a sporadic simple group.

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Uniform supertrees with extremal spectral radii
Wen-Huan WANG, Ling YUAN
Frontiers of Mathematics in China. 2020, 15 (6): 1211-1229.  
https://doi.org/10.1007/s11464-020-0873-6

摘要   PDF (439KB)

A supertree is a connected and acyclic hypergraph. We investigate the supertrees with the extremal spectral radii among several kinds of r-uniform supertrees. First, by using the matching polynomials of supertrees, a new and useful grafting operation is proposed for comparing the spectral radii of supertrees, and its applications are shown to obtain the supertrees with the extremal spectral radii among some kinds of r-uniform supertrees. Second, the supertree with the third smallest spectral radius among the r-uniform supertrees is deduced. Third, among the r-uniform supertrees with a given maximum degree, the supertree with the smallest spectral radius is derived. At last, among the r-uniform starlike supertrees, the supertrees with the smallest and the largest spectral radii are characterized.

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Integrable systems, multicomponent twisted Heisenberg-Virasoro algebra and its central extensions
Yemo WU, Xiurong XU, Dafeng ZUO
Frontiers of Mathematics in China. 2020, 15 (6): 1231-1243.  
https://doi.org/10.1007/s11464-020-0891-4

摘要   PDF (322KB)

Let DN be the multicomponent twisted Heisenberg-Virasoro algebra. We compute the second continuous cohomology group with coeficients in and study the bihamiltonian Euler equations associated to DN and its central extensions.

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Variable integral and smooth exponent Besov spaces associated to non-negative self-adjoint operators
Jingshi XU
Frontiers of Mathematics in China. 2020, 15 (6): 1245-1263.  
https://doi.org/10.1007/s11464-020-0886-1

摘要   PDF (337KB)

We introduce the variable integral and the smooth exponent Besov spaces associated to non-negative self-adjoint operators. Then we give the equivalent norms via the Peetre type maximal functions and atomic decomposition of these spaces.

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Pure projective modules and FP-injective modules over Morita rings
Meiqi YAN, Hailou YAO
Frontiers of Mathematics in China. 2020, 15 (6): 1265-1293.  
https://doi.org/10.1007/s11464-020-0877-2

摘要   PDF (350KB)

Let Λ(0,0)=(AANBBNAB) be a Morita ring, where the bimodule homomorphisms ϕand ψ are zero. We study the finite presentedness, locally coherence, pure projectivity, pure injectivity, and FP-injectivity of modules over Λ(0,0). Some applications are then given.

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Super-biderivations of not-finitely graded Lie superalgebras related to generalized super-Virasoro algebras
Zhuo ZHANG, Jixia YUAN, Xiaomin TANG
Frontiers of Mathematics in China. 2020, 15 (6): 1295-1306.  
https://doi.org/10.1007/s11464-020-0883-4

摘要   PDF (262KB)

We mainly study the super-biderivations of not-finitely graded Lie superalgebras related to generalized super-Virasoro algebras. In particular, we prove that all super-biderivations of not-finitely graded Lie superalgebras related to generalized super-Virasoro algebras are inner.

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Mean-field type forward-backward doubly stochastic differential equations and related stochastic differential games
Qingfeng ZHU, Lijiao SU, Fuguo LIU, Yufeng SHI, Yong’ao SHEN, Shuyang WANG
Frontiers of Mathematics in China. 2020, 15 (6): 1307-1326.  
https://doi.org/10.1007/s11464-020-0889-y

摘要   PDF (310KB)

We study a kind of partial information non-zero sum differential games of mean-field backward doubly stochastic differential equations, in which the coefficient contains not only the state process but also its marginal distribution, and the cost functional is also of mean-field type. It is required that the control is adapted to a sub-filtration of the filtration generated by the underlying Brownian motions. We establish a necessary condition in the form of maximum principle and a verification theorem, which is a sufficient condition for Nash equilibrium point. We use the theoretical results to deal with a partial information linear-quadratic (LQ) game, and obtain the unique Nash equilibrium point for our LQ game problem by virtue of the unique solvability of mean-field forward-backward doubly stochastic differential equation.

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