Generalized Takahashi manifolds

带边三维流形上广义瑟斯顿球面堆积的刚性

Rigidity of generalized Thurston's sphere packings on 3-dimensional manifolds with boundary

本文在带边三维流形上引入广义瑟斯顿球面堆积，证明其由组合标量曲率局部确定，并进一步证明在固定组合里奇曲率时具有无穷小刚性。

A Classification of subgroups of SL(4,R) Isomorphic to R^3 and Generalized Cusps in Projective 3 Manifolds

This paper uses work of Haettel to classify all subgroups of PGL(4,R) isomorphic to (R^3 , +), up to conjugacy. We use this to show there are 4 families of generalized cusps up to projective equivalence in dimension 3.

Lie Groupoids and Generalized Almost Subtangent Manifolds

In this paper, we show that there is a close relationship between generalized subtangent manifolds and Lie groupoids. We obtain equivalent assertions among the integrability conditions of generalized almost subtangent manifolds, the condition of compatibility of source and target maps of symplectic groupoids with symplectic form and generalized subtangent maps.

Generalized almost para-contact manifolds

In this paper, we introduce generalized almost para-contact manifolds and obtain normality conditions in terms of classical tensor fields. We show that such manifolds naturally carry certain Lie bialgebroid/quasi-Lie algebroid structures on them and we relate this new generalized manifolds with classical almost para-contact manifolds. The paper contains several examples.

Manifolds admitting special generic maps and their nice generalized multisections

We show that manifolds admitting special generic maps also admit nice generalized multisections. Special generic maps are natural generalized versions of Morse functions with exactly two singular points on closed manifolds, characterizing spheres whose dimensions are not $4$ topologically and the $4$-dimensional unit sphere, and canonical projections of unit spheres. They are shown to restrict the differentiable structures of spheres etc. and topologies of more general manifolds strongly by Saeki, Sakuma etc., followed by Nishioka, Wrazidlo etc. and followed by the author. Some elementary or i…

On generalized 3-manifolds which are not homologically locally connected

We show that the classical example $X$ of a 3-dimensional generalized manifold constructed by van Kampen is another example of not homologically locally connected (i.e. not HLC) space. This space $X$ is not locally homeomorphic to any of the compact metrizable 3-dimensional manifolds constructed in our earlier paper which are not HLC spaces either.

Generalized Hantzsche-Wendt Flat Manifolds

We study the family of closed Riemannian n-manifolds with holonomy group isomorphic to $Z_2^{n-1}$, which we call generalized Hantzsche-Wendt manifolds. We prove results on their structures, compute some invariants, and find relations between them, illustrated in graph connecting the family.

Generalized torsion and decomposition of 3-manifolds

A nontrivial element in a group is a generalized torsion element if some nonempty finite product of its conjugates is the identity. We prove that any generalized torsion element in a free product of torsion-free groups is conjugate to a generalized torsion element in some factor group. This implies that the fundamental group of a compact orientable $3$-manifold $M$ has a generalized torsion element if and only if the fundamental group of some prime factor of $M$ has a generalized torsion element. On the other hand, we demonstrate that there are infinitely many toroidal $3$-manifolds whose fund…

Generalized torsion elements and bi-orderability of 3-manifold groups

It is known that a bi-orderable group has no generalized torsion element, but the converse does not hold in general. We conjecture that the converse holds for the fundamental groups of 3-manifolds, and verify the conjecture for non-hyperbolic, geometric 3-manifolds. We also confirm the conjecture for some infinite families of closed hyperbolic 3-manifolds. In the course of the proof, we prove that each standard generator of the Fibonacci group F(2,m) (m>2) is a generalized torsion element.

Generalized fibre sums of 4-manifolds and the canonical class

In this paper we determine the integral homology and cohomology groups of a closed 4-manifold X obtained as the generalized fibre sum of two closed 4-manifolds M and N along embedded surfaces of genus g and self-intersection zero. If the homologies of the 4-manifolds are torsion free and the surfaces represent indivisible homology classes, we derive a formula for the intersection form of X. If in addition the 4-manifolds M and N are symplectic and the surfaces symplectically embedded we derive a formula for the canonical class of the symplectic fibre sum.

Generalized Kashaev invariants for knots in three manifolds

Kashaev's invariants for a knot in a three sphere are generalized to invariants of a knot in a three manifold. A relation between the newly constructed invariants and the hyperbolic volume of the knot complement is observed for some knots in lens spaces.

Quasiregular ellipticity of open and generalized manifolds

We study the existence of geometrically controlled branched covering maps from $\mathbb R^3$ to open $3$-manifolds or to decomposition spaces $\mathbb S^3/G$, and from $\mathbb S^3/G$ to $\mathbb S^3$.

The generalized Kummer construction and the cohomology rings of $G_2$-manifolds

We demonstrate how by using the intersection theory to calculate the cohomology of $G_2$-manifolds constructed by using the generalized Kummer construction. For one example we find the generators of the rational cohomology ring and describe the product structure.

三维流形上的新几何结构：手术与广义几何

New geometric structures on 3-manifolds: surgery and generalized geometry

本文通过广义几何中的$B_3$-广义复结构，证明了任意闭可定向三维流形均存在稳定结构（即一般地直到广义微分同胚为余辛结构），从而统一了余辛结构与正规几乎切触结构。

Topology of the iso-spectral real manifolds associated with the generalized Toda lattices on semisimple Lie algebras

This paper concerns the topology of isospectral real manifolds of certain Jacobi elements associated with real split semisimple Lie algebras. The manifolds are related to the compactified level sets of the generalized (nonperiodic) Toda lattice equations defined on the semisimple Lie algebras. We then give a cellular decomposition and the associated chain complex of the manifold by introducing colored Dynkin diagrams which parametrize the cells in the decomposition. We also discuss the Morse chain complex of the manifold.