Uno dei principali argomenti di interesse della geometria algebrica reale è lo studio degli insiemi algebrici e, in particolare, degli spazi topologici che ammettono modelli algebrici. In questo seminario descriverò alcune tecniche classiche della…
Eventi
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…
Brauer groups of moduli of hyperelliptic curves, via cohomological invariants – Roberto Pirisi (KTH Stockholm)
We use the theory of cohomological invariants for algebraic stacks to completely describe the Brauer group of the moduli stacks $H_g$ of genus $g$ hyperellitic curves over fields of characteristic zero, and the prime-to-$\mathsf{char}(k)$ part in…
Topological realization over $\mathbb{C}((t))$ via Kato-Nakayama spaces – Mattia Talpo (Università di Pisa)
I will report on some joint work with Piotr Achinger, about a “Betti realization” functor for varieties over the formal punctured disk $\mathsf{Spec}\mathbb{C}((t))$, i.e. defined by polynomials with coefficients in the field of formal Laurent…
Efficient iterative methods for the solution of Generalized Lyapunov Equations: Block vs. point Krylov projections, and other controversial decisions – Daniel Szyld (Temple University)
There has been a flurry of activity in recent years in the area of solution of matrix equations. In par- ticular, a good understanding has been reached on how to approach the solution of large scale Lya- punov equations. An effective way to solve…
Positivity of holomorphic vector bundles – Filippo Fagioli (Università di Roma “La Sapienza”)
Tra le nozioni di positività in geometria complessa è di particolare interesse quella di ampiezza. Un fibrato in rette su una varietà complessa si dice ampio se una sua qualche potenza tensoriale fornisce un embedding della varietà in uno spazio…
Generic derivations on o-minimal structures – Antongiulio Fornasiero (Università di Firenze)
Generic derivations on o-minimal structures Given an o-minimal theory, we define what is a derivation “compatible” with T. We show that the theory of compatible derivations has a model completion, and describe some of its properties.…
Displaying the cohomology of toric line bundles – Klaus Altmann (Freie Universität Berlin)
Line bundles L on projective toric varieties can be understood as formal differences of convex polyhedra in the character lattice. We show how it is possible to use this language for understanding the cohomology of L by studying the set-theoretic…
Codimension two cycles and unramified third cohomology for certain products of two varieties – Jean-Louis Colliot-Thelene (Université de Paris-Saclay)
We investigate the integral Tate conjecture for 1-cycles on the product of a curve and a surface over a finite field, under the assumption that the surface is geometrically $\mathsf{CH}_0$-trivial. By this we mean that over any algebraically closed…
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,…