Holonomy Lie algebra of a geometric lattice

Cup products, lower central series, and holonomy Lie algebras

We generalize basic results relating the associated graded Lie algebra and the holonomy Lie algebra from finitely presented, commutator-relators groups to arbitrary finitely presented groups. In the process, we give an explicit formula for the cup-product in the cohomology of a finite 2-complex, and an algorithm for computing the corresponding holonomy Lie algebra, using a Magnus expansion method. We illustrate our approach with examples drawn from a variety of group-theoretic and topological contexts, such as link groups, one-relator groups, and fundamental groups of orientable Seifert fibere…

Compact generation for Lie groupoids

Thirty years after the birth of foliations in the 1950's, André Haefliger has introduced a special property satisfied by holonomy pseudogroups of foliations on compact manifolds, called compact generation. Up to now, this is the only general property known about holonomy on compact manifolds. In this article, we give a Morita-invariant generalization of Haefliger's compact generation, from pseudogroups to object-separated Lie groupoids.

Geometric structures on orbifolds and holonomy representations

An orbifold is a topological space modeled on quotient spaces of a finite group actions. We can define the universal cover of an orbifold and the fundamental group as the deck transformation group. Let $G$ be a Lie group acting on a space $X$. We show that the space of isotopy-equivalence classes of $(G,X)$-structures on a compact orbifold $Σ$ is locally homeomorphic to the space of representations of the orbifold fundamental group of $Σ$ to $G$ following the work of Thurston, Morgan, and Lok. This implies that the deformation space of $(G, X)$-structures on $Σ$ is locally homeomorphic to the …

Projective Structures with (Quasi-)Hitchin Holonomy

In this paper we investigate the properties of the real and complex projective structures associated to Hitchin and quasi-Hitchin representations that were originally constructed using Guichard-Wienhard's theory of domains of discontinuity. We determine the topology of the underlying manifolds and we prove that some of these geometric structures are fibered in a special standard way. In order to prove these results, we give two new ways to construct these geometric structures: we construct them using gauge theory, flat bundles and Higgs bundles, and we also give a new geometric way to construc…

具有单值和乐群的闭共形平坦洛伦兹流形的分类

Classification of closed conformally flat Lorentzian manifolds with unipotent holonomy

本研究分类了n≥3维、PO(2,n)中单幂和乐的闭共形平坦洛伦兹流形，将其分为四类几何类型，明确了有限覆盖下的同胚形式，还进一步分类了其中容许本质共形流的两类流形。

D-模与可解李叶状结构

D-modules and Solvable Lie Foliations

本文从D-模理论出发研究紧致流形上的可解李叶状结构，通过计算三类叶状结构的D-不规则度，证明和乐群非多循环性等价于导出环高阶上同调非消失，建立几何与D-模不变量的新联系。