共查询到20条相似文献,搜索用时 15 毫秒
1.
Steven Hurder 《Topology and its Applications》2006,153(12):2135-2154
We prove that if F is a C1-foliation of a compact manifold M with finite transverse saturated LS category, , then F has a compact leaf. In contrast, we show that if F is expansive on some non-trivial minimal set of F, then . Examples of foliations are given to illustrate the main results of the paper. 相似文献
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We classify the solutions of the equation Δu+aeu=0 in the half-plane that satisfy the Neumann boundary condition ∂u/∂t=ceu/2 on . An analogous problem in the once punctured disc D∗⊂R2 is also solved. 相似文献
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César Camacho 《Topology and its Applications》2007,154(6):1032-1040
A closed, connected oriented three-manifold supporting a codimension one oriented smooth foliation with Morse singularities having more centers than saddles and without saddle connections is diffeomorphic to the three-sphere. The use of the Reeb Stability theorem in place of the Poincaré-Bendixson theorem paves the way to a three-dimensional version, for foliations with singularities of Morse type, of a classical result of Haefliger. Finally, we give an example of a codimension one C∞ foliation in the closed ball , with only one singularity which is of saddle type 2-2 and transverse to the boundary S3=∂B4. 相似文献
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Linear Fractional Maps of the Unit Ball: A Geometric Study 总被引:1,自引:0,他引:1
Cinzia BisiFilippo Bracci 《Advances in Mathematics》2002,167(2):265-287
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In this article we classify all positive finite energy solutions of the equation in Rn where and a point x∈Rn is denoted as x=(y,z)∈Rk×Rn-k. As a consequence we obtain the best constant and extremals of a related Hardy-Sobolev inequality. 相似文献
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Zhi-Hong Sun 《Journal of Number Theory》2009,129(3):499-550
Let be a prime and a,b∈Z with a2+b2≠p. Suppose p=x2+(a2+b2)y2 for some integers x and y. In the paper we develop the calculation technique of quartic Jacobi symbols and use it to determine . As applications we obtain the congruences for modulo p and the criteria for (if ), where {Un} is the Lucas sequence given by U0=0, U1=1 and Un+1=bUn+k2Un−1(n?1). We also pose many conjectures concerning , or . 相似文献
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For any closed oriented surface Σg of genus g?3, we prove the existence of foliatedΣg-bundles over surfaces such that the signatures of the total spaces are non-zero. We can arrange that the total holonomy of the horizontal foliations preserve a prescribed symplectic form ω on the fiber. We relate the cohomology class represented by the transverse symplectic form to a crossed homomorphism which is an extension of the flux homomorphism from the identity component to the whole group of symplectomorphisms of Σg with respect to the symplectic form ω. 相似文献
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Given a generalized Robertson-Walker spacetime whose warping function verifies a certain convexity condition, we classify strongly stable spacelike hypersurfaces with constant mean curvature. More precisely, we will show that given a closed, strongly stable spacelike hypersurface of with constant mean curvature H, if the warping function ? satisfying ?″?max{H?′,0} along M, then Mn is either maximal or a spacelike slice Mt0={t0}×F, for some t0∈I. 相似文献
11.
Alex V. Kontorovich 《Journal of Number Theory》2006,117(1):1-13
For every positive integer n, the quantum integer [n]q is the polynomial [n]q=1+q+q2+?+qn-1. A quadratic addition rule for quantum integers consists of sequences of polynomials , , and such that for all m and n. This paper gives a complete classification of quadratic addition rules, and also considers sequences of polynomials that satisfy the associated functional equation . 相似文献
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Steve Seif 《Journal of Pure and Applied Algebra》2008,212(5):1162-1174
A classic result from the 1960s states that the asymptotic growth of the free spectrum of a finite group is sub-log-exponential if and only if is nilpotent. Thus a monoid is sub-log-exponential implies , the pseudovariety of semigroups with nilpotent subgroups. Unfortunately, little more is known about the boundary between the sub-log-exponential and log-exponential monoids.The pseudovariety consists of those finite semigroups satisfying (xωyω)ω(yωxω)ω(xωyω)ω≈(xωyω)ω. Here it is shown that a monoid is sub-log-exponential implies . A quick application: a regular sub-log-exponential monoid is orthodox. It is conjectured that a finite monoid is sub-log-exponential if and only if it is , the finite monoids in having nilpotent subgroups. The forward direction of the conjecture is proved; moreover, the conjecture is proved for when is completely (0)-simple. In particular, the six-element Brandt monoid (the Perkins semigroup) is sub-log-exponential. 相似文献
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Jie Du 《Journal of Pure and Applied Algebra》2011,215(11):2715-2737
We introduce the notion of quantum Schur (or q-Schur) superalgebras. These algebras share certain nice properties with q-Schur algebras such as the base change property, the existence of canonical Z[v,v−1]-bases, the duality relation with Manin’s quantum matrix superalgebra A(m|n), and the bridging role between quantum enveloping superalgebras of gl(m|n) and the Hecke algebras of type A. We also construct a cellular -basis and determine its associated cells, called supercells, in terms of a Robinson-Schensted-Knuth supercorrespondence. In this way, we classify all irreducible representations over via supercell modules. 相似文献
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For the steady-state solution of an integral-differential equation from a two-dimensional model in transport theory, we shall derive and study a nonsymmetric algebraic Riccati equation B--XF--F+X+XB+X=0, where , and with a nonnegative matrix P, positive diagonal matrices D±, and nonnegative parameters f, and . We prove the existence of the minimal nonnegative solution X∗ under the physically reasonable assumption , and study its numerical computation by fixed-point iteration, Newton’s method and doubling. We shall also study several special cases; e.g. when and P is low-ranked, then is low-ranked and can be computed using more efficient iterative processes in U and V. Numerical examples will be given to illustrate our theoretical results. 相似文献
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H. Giacomini 《Journal of Differential Equations》2005,213(2):368-388
We consider a planar differential system , , where P and Q are C1 functions in some open set U⊆R2, and . Let γ be a periodic orbit of the system in U. Let f(x,y):U⊆R2→R be a C1 function such that
20.
Steven Broad 《Journal of Differential Equations》2010,249(11):2688-3812
Let be the Cauchy-Riemann operator and f be a Cn real-valued function in a neighborhood of 0 in R2 in which for all z≠0. In such cases, is known as a Loewner vector field due to its connection with Loewner's conjecture that the index of such a vector field is bounded above by n. The n=2 case of Loewner's conjecture implies Carathéodory's conjecture that any C2-immersion of S2 into R3 must have at least two umbilics. Recent work of F. Xavier produced a formula for computing the index of Loewner vector fields when n=2 using data about the Hessian of f. In this paper, we extend this result and establish an index formula for for all n?2. Structurally, our index formula provides a defect term, which contains geometric data extracted from Hessian-like objects associated with higher order derivatives of f. 相似文献