Degeneracy of holomorphic curves in surfaces

Let X be a complex projective algebraic manifold of dimension 2 and let D1,…,Du be distinct irreducible divisors on X such that no three of them share a common point. Let f: C→X\(U1≤i≤uDi) be a holomorphic map. Assume that u≥4 and that there exist positive integers n1,…,nu, c such that ninj(Di.Dj) = c for all pairs i, j. Then f is algebraically degenerate, i.e. its image is contained in an algebraic curve on X.     

Uniqueness theorems for holomorphic curves sharing moving hypersurfaces

In this article, we prove some uniqueness theorems for non-constant holomorphic curves of ? into ? ⁿ (?) sharing moving hypersurfaces in general position for the Veronese embedding, ignoring multiplicity.     

Uniqueness theorem for algebraic curves on compact Riemann surfaces

In this paper, we prove a uniqueness theorem for algebraic curves from a compact Riemann surface into complex projective spaces.     

Second main theorem and uniqueness theorem with moving targets on parabolic manifolds

In this paper, with the motivation from Diophantine approximation, a truncated second main theorem is established for meromorphic maps from M   into P(V)$\mathbb{P}(V)$ with moving targets _gj:M→P(V^?)$g_j:M\to \mathbb{P}(V^{?})$, 1≤j≤q$1\le j\le q$, where M is a parabolic manifold and V is a Hermitian vector space. As an application of this second main theorem, a uniqueness theorem without counting multiplicities is given.     

The Cayley-Bacharach theorem for continuous piecewise algebraic curves over cross-cut triangulations

A piecewise algebraic curve is a curve determined by the zero set of a bivariate spline function. In this paper, we propose the Cayley-Bacharach theorem for continuous piecewise algebraic curves over cross-cut triangulations. We show that, if two continuous piecewise algebraic curves of degrees m and n respectively meet at mnT distinct points over a cross-cut triangulation, where T denotes the number of cells of the triangulation, then any continuous piecewise algebraic curve of degree m + n − 2 containing all but one point of them also contains the last point.     

Invariant algebraic curves and rational first integrals of holomorphic foliations in CP(2)

In this paper, using the tools of algebraic geometry we provide sufficient conditions for a holomor-phic foliation in CP(2) to have a rational first integral. Moreover, we obtain an upper bound of the degrees of invariant algebraic curves of a holomorphic foliation in CP(2). Then we use these results to prove that any holomorphic foliation of degree 2 does not have cubic limit cycles.     

A New Notion of Defect for Holomorphic Curves and Their Sequences

In this paper, we study transcendental curves in ⁿ and also infinite sequences of rational curves using methods of the value distribution theory of holomorphic mappings and, in particular, the notions of Nevanlinna and Valiron defects. In contrast to the classical case, we study the defects of points in ⁿ rather than of divisors. It is shown how the main notions of the theory should be changed to make them meaningful in this context. Analogs of the main theorems are proved. It is established that the sets of defective points are sparse in the sense of an adequately introduced Hausdorff h-measure.     

The second main theorem for moving targets

The defect relation for holomorphic maps in respect to slowly moving target hyperplanes in is proved. The sharp defect boundn+1 is obtained. Communicated by Yoram Sagher     

An extension of Picard's theorem for meromorphic functions of small hyper-order

A version of the second main theorem of Nevanlinna theory is proved, where the ramification term is replaced by a term depending on a certain composition operator of a meromorphic function of small hyper-order. As a corollary of this result it is shown that if n∈N and three distinct values of a meromorphic function f of hyper-order less than 1/n² have forward invariant pre-images with respect to a fixed branch of the algebraic function τ(z)=z+αn−1z1−1/n+?+α₁z1/n+α₀ with constant coefficients, then f○τ≡f. This is a generalization of Picard's theorem for meromorphic functions of small hyper-order, since the (empty) pre-images of the usual Picard exceptional values are special cases of forward invariant pre-images.     

Stokes' theorem for domains with fractal boundary

In this paper, integrals of second kind over a rectifiable curve or a piecewise smooth surface are extended to continuous fractal curves and surfaces. Theorems for the existence of these integrals are proved. Green's, Gauss' and Stokes' theorems are developed for domains with fractal boundaries.     

An isomorphism theorem for Teichmüller curves

It is proved that for any Fuchsian group Γ such that ℍ/Γ is a hyperbolic Riemann surface, the Teichmüller curve V(Γ) has a unique complex manifold structure so that the natural projection of the Bers fiber space F(Γ) onto V(Γ) is holomorphic with local holomorphic sections. An isomorphism theorem for Teichmüller curves is deduced, which generalizes a classical result that the Teichmüller curve V(Γ) depends only on the type of Γ and not on the orders of the elliptic elements of Γ when ℍ/Γ is a compact hyperbolic Riemann surface.     

A speciality theorem for curves in P<Superscript>5</Superscript>

Let be an integral projective curve. One defines the speciality index e(C) of C as the maximal integer t such that , where ω _C denotes the dualizing sheaf of . Extending a classical result of Halphen concerning the speciality of a space curve, in the present paper we prove that if is an integral degree d curve not contained in any surface of degree  < s, in any threefold of degree  < t, and in any fourfold of degree  < u, and if , then Moreover equality holds if and only if C is a complete intersection of hypersurfaces of degrees u, , and . We give also some partial results in the general case , .      

Wong's comparison theorem for second order linear dynamic equations on time scales

We obtain Wong-type comparison theorems for second order linear dynamic equations on a time scale. The results obtained extend and are motivated by Wong's comparison theorems. As a particular application of our results, we show that the difference equation

     

一类二阶非线性微分方程解的零点比较定理

通过建立几个微分不等式将经典的微分方程零点比较定理推广到二阶非线性微分方程,得到若干新的结论.     

二阶非线性微分方程解的Sturm比较定理

通过几个微分不等式建立了一类非线性微分方程解的Sturm比较定理,推广了一些经典的结论。