Since the volume of a hyperbolic manifold is often regarded as a measure of its complexity, it is interesting to study the examples of minimal volume. The 2 and 3-dimensional cases are well understood. In dimension four there is an abundance of…
Categoria evento: Geometry Seminar
Morfismo traccia e deformazioni di coppie (varieta’, fascio coerente). – Marco Manetti (Universita\’ di Roma “La Sapienza”)
Dato un fascio coerente F su una varieta’ liscia proiettiva X, viene determinata l’algebra di Lie differenziale graduata che controlla le deformazioni della coppia (X,F). Viene poi introdotto un morfismo di traccia tra opportuni fasci di operatori…
On corks with low shadow-complexity – Hironobu Naoe (Tohoku University, Japan)
A cork is a contractible Stein domain that gives arise to exotic pairs of 4-manifolds. The first example was found by Akbulut. It is known that any two exotic, simply-connected, closed 4-manifolds are related by a cork twist. We show that there are…
Moduli of curves with principal and spin bundles: singularities and global geometry – Mattia Galeotti (Universite\’ “Pierre et Marie Curie”, Parigi)
Abstract: In a series of recent papers, Chiodo, Farkas and Ludwig carried out a deep analysis of the singular locus of the moduli space of stable (twisted) curves with an l-torsion line bundle. They showed that for l ≤ 6 and different from 5…
Kodaira fibrations with small signature – Sönke Rollenske (Univ. Marburg (Germania) )
Kodaira fibrations are surfaces of general type with a non-isotrivial fibration, which are differentiable fibre bundles. First examples were constructed by Kodaira and Atiyah to show that the signature need not be multiplicative in fibre bundles. We…
Elliptic diffeomorphisms of symplectic 4-manifolds – Gleb Smirnov (International School for Advanced Studies (Trieste, Italy))
In his PhD thesis, Paul Seidel found examples of symplectomorphisms which are smoothly isotopic to the identity, but not isotopic to the identity within the symplectomorphism group. These symplectomorphisms are known as Dehn twists, and they exist…
Embedding arithmetic hyperbolic manifolds – Leone Slavich (Università di Pisa)
Given an n-dimensional hyperbolic manifold M, it is reasonable to ask whether or not it can be realized as a totally geodesic, embedded submanifold of an (n+1)-dimensional hyperbolic manifold. If this is true, we say that M geodesically embeds.…
New perspectives on lattice gauge field theories – Stéphane Baseilhac (Université de Montpellier)
Venue Sala Seminari (Dip. Matematica). Abstract…
Entropy and length rigidity of negatively curved manifolds of finite volume – Andrea Sambusetti (Roma La Sapienza)
The problems of conjugacy rigidity and of entropy rigidity have a long history, with major breakthroughs in the last twenty years, for negatively curved compact manifolds and symmetric spaces. On the other hand, little is known for finite volume…
How to “synthesize” sub-fixed point sets into the global one just by looking inside groups? – Masato Mimura (Tohoku university e EPF Lausanne)
Consider a group G action on a metric space X by isometries, andsubgroups M_1,…, M_l. One interesting and important problem isto studyconditions underwhichnon-emptyness of each M_i-fixed points ensures thatof global (G-)fixed points. One extreme…