By Margulis’ Lemma, a finite-volume complete hyperbolic n-manifold has a finite number of ends called cusps, each of which is diffeomorphic to the product of a flat (n-1)-manifold with the half-line. These flat manifolds are called cusp sections,…
Categoria evento: Geometry Seminar
Obstructing sliceness of knots through branched covers – Andras Stipsicz (Alfréd Rényi Institute of Mathematics, Budapest)
slice knots (bounding smooth disks in the 4-space) play an important role in knot theory. They can be studied through examining the branched cover of the three-sphere along the given knot. In the lecture we describe two results around these…
Embedding hyperbolic manifolds – Leone Slavich (Università di Pavia)
A complete hyperbolic n-manifold geodesically embeds if it realized a totally geodesic embedded hypersurface in an (n+1)-hyperbolic manifold. On one hand, we know no general obstruction to the fact that a hyperbolic manifold of dimension n>2 embeds,…
Contact structures on lens spaces and their Stein fillings – Edoardo Fossati (SNS)
Everything has been said about Stein fillings of lens spaces when they are endowed with their standard (tight) contact structure. Nevertheless, lens spaces support many more tight structures, that are all classified, but for which a complete list of…
On the reduced Dijkgraaf-Witten invariant of knots in the Bloch group of Fp – Hiroaki Karuo (RIMS, Kyoto )
For a closed oriented 3-manifold $M$, a discrete group $G$, a 3-cocycle $\alpha$ of $G$, and a representation $\rho \colon \pi_1(M) \to G$, the Dijkgraaf–Witten invariant is defined to be $\rho^\ast \alpha [M]$, where $[M]$ is the fundamental class…
Geometric finiteness in Hadamard manifolds – Beibei Liu (MPIM Bonn)
In this talk, we will focus on negatively pinched Hadamard manifolds which are complete, simply connected Riemannian manifolds with sectional curvature ranging between two negative constants. We use the techniques in geometric group theory to…
Deligne-Mostow lattices and come metrics on the sphere – Irene Pasquinelli (Paris Jussieu)
Finding lattices in PU(n,1) has been one of the major challenges of the last decades. One way of constructing a lattice is to give a fundamental domain for its action on the complex hyperbolic space. One approach, successful for some lattices,…
Metric Lie groups – Sebastiano Nicolussi Golo (Università di Padova)
The objects of the talk are locally compact metric spaces that are isometrically homogeneous. I will discuss their quasi-isometric classification and the characterization of those spaces that admit dilations. They are not assumed to be length…
Massimo volume di poliedri iperbolici – Giulio Belletti (SNS Pisa)
In questo seminario esporrò la dimostrazione del teorema sul massimo volume dei poliedri iperbolici, introdotta nello scorso seminario. La dimostrazione si basa su un attento studio delle possibili degenerazioni che un poliedro può subire in seguito…
Il massimo volume dei poliedri iperbolici – Giulio Belletti (SNS)
Qual è il volume massimo dei poliedri iperbolici con combinatoria fissata? Un risultato classico dice che il massimo volume ottenuto dai simplessi iperbolici è quello del simplesso regolare con tutti i vertici all’infinito. Purtroppo un risultato…