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Autumn Semester 2018

Date / Time Speaker Title Location
12 October 2018
15:00-16:00 		Federico Vigolo
University of Oxford
Event Details

Geometry Graduate Colloquium

Title Expander graphs and how to find them
Speaker, Affiliation Federico Vigolo, University of Oxford
Date, Time 12 October 2018, 15:00-16:00
Location HG G 19.2
Abstract Expander graphs are finite graphs that are both sparse and highly connected. These objects are interesting for a number of reasons and have diverse applications. In this talk I will introduce the topic of expander graphs and I will explain some explicit constructions of families of expanders.
Expander graphs and how to find themread_more
HG G 19.2
18 October 2018
15:00-16:00 		Giuliano Basso
ETH Zurich, Switzerland
Event Details

Geometry Graduate Colloquium

Title Lipschitz extensions to finitely many points
Speaker, Affiliation Giuliano Basso, ETH Zurich, Switzerland
Date, Time 18 October 2018, 15:00-16:00
Location HG G 19.2
Abstract We consider Lipschitz maps with values in quasi-metric spaces and extend such maps to finitely many points. We prove that in this context every 1-Lipschitz map admits an extension such that its Lipschitz constant is bounded from above by the number of added points plus one. If time permits, we discuss applications to metric transforms.
Lipschitz extensions to finitely many pointsread_more
HG G 19.2
1 November 2018
15:00-16:00 		Dr. Jagna Wisniewska
ETH Zurich, Switzerland
Event Details

Geometry Graduate Colloquium

Title Algebraic invariants of Hamiltonian dynamical systems
Speaker, Affiliation Dr. Jagna Wisniewska, ETH Zurich, Switzerland
Date, Time 1 November 2018, 15:00-16:00
Location HG G 19.2
Abstract Modern symplectic geometry started as a mathematical formulation of classical mechanics. Examples of Hamiltonian dynamical systems arise in celestial mechanics or electromagnetism. However, even though the equations are known, explicit computations of the trajectories might often be too complex. In my talk I will introduce tools from algebraic topology (Morse homology) and variational analysis (action functional) and she how they can be combined to investigate the evolution of Hamiltonian systems in time.
Algebraic invariants of Hamiltonian dynamical systemsread_more (CANCELLED)
HG G 19.2
8 November 2018
15:00-16:00 		Dr. Jagna Wisniewska
ETH Zurich, Switzerland
Event Details

Geometry Graduate Colloquium

Title Algebraic invariants of Hamiltonian dynamical systems
Speaker, Affiliation Dr. Jagna Wisniewska, ETH Zurich, Switzerland
Date, Time 8 November 2018, 15:00-16:00
Location HG G 19.2
Abstract Modern symplectic geometry started as a mathematical formulation of classical mechanics. Examples of Hamiltonian dynamical systems arise in celestial mechanics or electromagnetism. However, even though the equations are known, explicit computations of the trajectories might often be too complex. In my talk I will introduce tools from algebraic topology (Morse homology) and variational analysis (action functional) and she how they can be combined to investigate the evolution of Hamiltonian systems in time.
Algebraic invariants of Hamiltonian dynamical systemsread_more
HG G 19.2
22 November 2018
15:00-16:00 		Hubert Sidler
Université de Fribourg
Event Details

Geometry Graduate Colloquium

Title Harmonic maps between Hadamard manifolds
Speaker, Affiliation Hubert Sidler, Université de Fribourg
Date, Time 22 November 2018, 15:00-16:00
Location HG G 19.2
Abstract Harmonic maps are a natural generalization of harmonic functions. They appear in physics, but are also an important tool in rigidity theory. In my talk I will introduce harmonic maps and focus on the problem of existence in the setting of Hadamard manifolds. In order to do this, one needs a good formulation of the “correct” setting. I will present recent results by Benoist-Hulin and others resolving a conjecture by Schoen from 1980 which shows that the “natural” setting works well for these particular cases.
Harmonic maps between Hadamard manifoldsread_more
HG G 19.2
29 November 2018
15:00-16:00 		Paul Creutz
Universität Köln
Event Details

Geometry Graduate Colloquium

Title Quadratic Isoperimetric Inequalities in Metric Spaces
Speaker, Affiliation Paul Creutz, Universität Köln
Date, Time 29 November 2018, 15:00-16:00
Location HG G 19.2
Abstract A metric space X satisfies quadratic isoperimetric inequality if every closed curve in X bounds a disc of area quadratically bounded by its length. Metric spaces satisfying quadratic isoperimetric inequality with small constants may be recognized to satisfy different notions of nonpositive curvature like CAT(0) condition or Gromov hyperbolictiy. In my talk I will give a short introduction and overview over such results and then especially focus on Banach spaces (or more generally on spaces admitting conical geodesic bicombings).
Quadratic Isoperimetric Inequalities in Metric Spacesread_more
HG G 19.2
* 13 December 2018
15:30-16:30 		Merlin Incerti-Medici
Universität Zürich
Event Details

Geometry Graduate Colloquium

Title A short introduction to CAT(0) cube complexes
Speaker, Affiliation Merlin Incerti-Medici, Universität Zürich
Date, Time 13 December 2018, 15:30-16:30
Location HG G 19.2
Abstract After Gromov's work on hyperbolic groups in the 80s, there has been a lot of work to understand groups based on the non-positively curved spaces they act on (nicely). This work has proven to be successful if one restricts to specific classes of non-positively curved spaces that have additional nice properties. One of the most prominent of these classes today are CAT(0) cube complexes; cube complexes whose induced metric has non-positive curvature. We will define CAT(0) cube complexes and the most basic notions that are used in their study. We will discuss their relationship to wall spaces and properties as median spaces. We will then move on to several classes of cubulable groups - groups that act properly and cocompactly by cube-isomorphisms on a CAT(0) cube complex - and present ways to construct cube complexes out of a group in such a class. We will briefly speak about CAT(0) cube complexes call to fame from the proof of the virtual Haken and the virtual fibered conjecture and, if time permits, present some recent results on the rigid structure of 'nice' group actions on 'nice' CAT(0) cube complexes.
A short introduction to CAT(0) cube complexesread_more
HG G 19.2

Note: events marked with an asterisk (*) indicate that the time and/or location are different from the usual time and/or location.

Organizers: Yannick Krifka, Davide Spriano

Archive: SS 24 AS 23 SS 23 AS 22 SS 22 AS 21 SS 21 AS 20 SS 20 AS 19 AS 18 SS 18

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