排序方式: 共有21条查询结果,搜索用时 15 毫秒
1.
2.
Extending our earlier results, we prove that certain tight contact structures on circle bundles over surfaces are not symplectically semi–fillable, thus confirming a conjecture of Ko Honda.Mathematics Subject Classification (2000)57R57, 57R17Partially supported by MURST and member of EDGE, Research Training Network HPRN-CT-2000-00101, supported by The European Human Potential ProgrammePartially supported by OTKA T034885 相似文献
3.
We determine the combinations of singular fibers a locally holomorphic elliptic fibration on the rational elliptic surface can admit. This problem has been answered for globally holomorphic elliptic fibrations by Persson and Miranda [12], [9]; we compare our methods and results to theirs. In particular, we find combinations of singular fibers which can be realized by locally holomorphic fibrations but not by globally holomorphic ones. 相似文献
4.
Burak Ozbagci Andrá s I. Stipsicz 《Proceedings of the American Mathematical Society》2004,132(5):1549-1558
Infinitely many contact 3-manifolds each admitting infinitely many pairwise non-diffeomorphic Stein fillings are constructed. We use Lefschetz fibrations in our constructions and compute their first homologies to distinguish the fillings.
5.
We show that for rational surface singularities with odd determinant the -invariant defined by W. Neumann is an obstruction for the link of the singularity to bound a rational homology 4-ball. We identify the -invariant with the corresponding correction term in Heegaard Floer theory.
6.
András I. Stipsicz 《Acta Mathematica Hungarica》2002,95(4):299-307
Using the theory of Lefschetz fibrations and recent advances in mapping class group theory, surface bundles over surfaces with nonzero signature and small base genus are constructed. In particular, a genus-5 fibration over the surface of genus 26 with nonzero signature is given –- improving former results on the possible base genera for surface bundles over surfaces with nonzero signature. 相似文献
7.
In this paper, we give a necessary combinatorial condition fora negative-definite plumbing tree to be suitable for rationalblowdown, or to be the graph of a complex surface singularitywhich admits a rational homology disk smoothing. New examplesof surface singularities with rational homology disk smoothingsare also presented; these include singularities with resolutiongraph having valency 4 nodes. Received July 25, 2007. 相似文献
8.
We prove that Lefschetz fibrations admitting a section of square cannot be decomposed as fiber sums. In particular, Lefschetz fibrations on symplectic 4-manifolds found by Donaldson are indecomposable. This observation also shows that symplectic Lefschetz fibrations are not necessarily fiber sums of holomorphic ones.
9.
Burak Ozbagci Andrá s I. Stipsicz 《Proceedings of the American Mathematical Society》2000,128(10):3125-3128
We construct noncomplex smooth 4-manifolds which admit genus-2 Lefschetz fibrations over . The fibrations are necessarily hyperelliptic, and the resulting 4-manifolds are not even homotopy equivalent to complex surfaces. Furthermore, these examples show that fiber sums of holomorphic Lefschetz fibrations do not necessarily admit complex structures.
10.
Two constructions of contact manifolds are presented: (i) products of S
1 with manifolds admitting a suitable decomposition into two exact symplectic pieces and (ii) fibre connected sums along isotropic
circles. Baykur has found a decomposition as required for (i) for all closed, oriented 4-manifolds. As a corollary, we can
show that all closed, oriented 5-manifolds that are Cartesian products of lower-dimensional manifolds carry a contact structure.
For symplectic 4-manifolds we exhibit an alternative construction of such a decomposition; this gives us control over the
homotopy type of the corresponding contact structure. In particular, we prove that
\mathbb CP2×S1{{\mathbb {CP}}^2\times S^1} admits a contact structure in every homotopy class of almost contact structures. The existence of contact structures is also
established for a large class of 5-manifolds with fundamental group
\mathbbZ2{{\mathbb{Z}}_2} . 相似文献