We give counterexamples to a conjecture of Bowditch that if a non-elementary type-preserving representation ρ : π1(Σg,n) → P SL(2; R) of a punctured surface group sends every non-peripheral simple closed curve to a hyperbolic element, then ρ must be…
Categoria evento: Geometry Seminar
Gromov’s main inequality and macroscopic scalar curvature – Roman Sauer (Karlsruhe)
We discuss generalizations of Gromov’s main inequality which states an inequality between Riemannian and simplicial volume under a lower curvature Ricci curvature bound. According to Gromov one might be able to replace Ricci by scalar curvature. We…
Moduli and periods beyond the classical cases – Radu Laza ((Stony Brook University))
Radu Laza (Stony Brook University) Title: Moduli and periods beyond the classical cases Abstract: The period map is the main tool for studying the moduli spaces of abelian varieties and K3 surfaces (and a few other related cases such as…
Pretzel links, mutation, and the slice-ribbon conjecture – Paolo Aceto ( Rényi Institute (Budapest) )
We show that the mutant 2-component pretzel links P(p,q,-q,-p) and P(p,q,-p,-q) are not concordant for any distinct odd integers p and q greater than 1. As a corollary, we obtain a proof of the slice-ribbon conjecture for 4-stranded 2-component…
Entropia e finitezza per gruppi con scomposizioni acilindriche – Filippo Cerocchi (Università di Roma)
Si consideri la famiglia dei gruppi finitamente generati che ammettono una scomposizione k-acilindrica, non-elementare (l’acilindricità è da intendersi nel senso di Sela). Mostreremo l’esistenza di una funzione (esplicita) f( – ;k):N—>N,…
An introduction to ideal simplicial volume – Marco Moraschini (Università di Pisa)
The simplicial volume is a homotopy invariant of compact manifolds introduced in 1982 by Gromov in his pioneering paper “Volume and Bounded Cohomology”. Roughly speaking, the simplicial volume measures how difficult is to describe a manifold in…
Geometry of alternating links on surfaces – Joshua Howie (Monash University)
We study links in 3-manifolds which have alternating diagrams onto orientable surfaces of positive genus. When the diagram is sufficiently complicated, we are able to obtain topological and geometrical information about the link exterior. In…
Algebre skein di superfici a bordo – Francois Costantino (Université de Toulouse)
(Collaborazione con Thang Le) Le algebre skein delle superfici chiuse sono oggetti estremamente ricchi di struttura e studiati.Recentemente, partendo da lavori di Bonahon-Wong e di Muller, Thang Le ha definito una versione delle algebre skein per…
Computational Geometry and Topology for Data Analysis – Daniela Giorgi (CNR, Pisa)
Il seminario introdurrà alcune problematiche classiche dell’analisi di dati digitali multidimensionali, e in particolare di modelli 3D: segmentazione, classificazione, confronto. Vedremo come la geometria e la topologia computazionale si prestino…
Equivariant hyperbolization and applications – Danny Ruberman (Brandeis University)
Given a closed 3-manifold Y with the action of a finite group G, we show how to find a closely related hyperbolic G-manifold Y’. The two manifolds are related by an invertible equivariant homology cobordism; a cobordism from Y to Y’ is invertible if…