Conferences, Research Colloquia & Seminars, Defenses, and other events

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Geometry Seminar

This is the research seminar of the group and focuses on recent research in (differential) geometry; during the semester the seminar is usually scheduled to take place on Wednesday at 16:00 in the Zeichensaal 1 or online. If you are interested in giving a talk, please contact the organizers: Ivan Izmestiev

Student Seminars

These seminars are usually part of the assessment and are open to the public, in particular, to interested students; topics typically focus on geometry but cover a wider range of areas, depending on the students' and the advisor's interests. Presentations are often delivered in German.

This semester's schedule

Talks in the geometry seminar

(hover/tap name or title to view more information)

03 May 2023: Geometry seminar
Mohammad Ivaki (TU Wien): TBA

Winter term 2022/23

Hans Havlicek with participants, 9 Dec 2022
photograph © Gunter Weiß

Hellmuth Stachel, 18 Nov 2022
photograph © Georg Glaeser


09 Dez 2022, Zeichensaal 3: Festkolloquium
zum 70. Geburtstag von Hans Havlicek


13:30 - 14:30
Silvia Pianta (Universita Cattolica del Sacre Cuore, Brescia): 1984, and beyond ... through joint Hanswers around parallelisms
14:30 - 15:30
Markus Stroppel (Universität Stuttgart): Projective geometry in an algebraist's toolbox
15:30 - 16:00
16:00 - 17:00
Mark Pankov (University Warmia and Mazury, Olsztyn): One result of Hans and a non-bijective version of Wigner theorem
17:00 - 18:00
Corrado Zanella (Universita di Padova): Incidence properties of algebraic varieties

18 Nov 2022, Zeichensaal 3: Festkolloquium
zum 80. Geburtstag von Hellmuth Stachel


13:15 - 14:00
Eröffnung und Laudatio von Otto Röschel
14:00 - 15:00
Johannes Wallner (TU Graz): Flexible nets and discrete differential geometry
15:00 - 16:00
Georg Glaeser (Universität für angewandte Kunst Wien): Forty years between descriptive and computational geometry: the universe of spatial imagination
16:00 - 16:30
16:30 - 17:30
Hans-Peter Schröcker (Universität Innsbruck): Devil in paradise II - recent results in motion factorization
17:30 - 18:30
Giorgio Figliolini (Universität Cassino): Kinematics of mechanisms with higher-pairs: fundamentals and applications
Abendessen im Restaurant Waldviertlerhof, Schönbrunnerstr. 20, 1050 Wien

Talks in the geometry seminar

(hover/tap name or title to view more information)

21 Feb 2023: Geometry seminar 15:00, ZS1
Alex Fairley (TU Berlin): Circular nets with spherical parameter lines


In the context of discrete differential geometry, circular nets provide a discretisation of curvature line parametrisations. In this talk, we will present incidence theorems to construct circular nets with spherical parameter lines. And we will present geometric properties of circular nets with spherical parameter lines. We will compare them with the classical properties of surfaces with spherical curvature lines. These are classical surfaces that were intensely studied in the 19th century.
23 Jan 2023: Geometry seminar
Sergey Agafonov (Sao Paulo State University): Confocal conics and 4-webs of maximal rank


Confocal conics form an orthogonal net. Supplementing this net with one of the following: 1) the net of Cartesian coordinate lines aligned along the principal axes of conics, 2) the net of Apollonian pencils of circles whose foci coincide with the foci of conics, 3) the net of tangents to a conic of the confocal family, we get a planar 4-web. We show that each of these 4-webs is of maximal rank and characterize confocal conics from the web theory viewpoint.
12 Dec 2022
16 Jan 2023: Geometry seminar
Christian Müller (TU Wien): The Geometry of Discrete AGAG-Webs in Isotropic 3-Space


We investigate webs from the perspective of the geometry of webs on surfaces in three dimensional space. Our study of AGAG-webs is motivated by architectural applications of gridshell structures where four families of manufactured curves on a curved surface are realizations of asymptotic lines and geodesic lines. We describe all discrete AGAG-webs in isotropic space and propose a method to construct them. Furthermore, we prove that some sub-nets of an AGAG-web are timelike minimal surfaces in Minkowski space and can be embedded into a one-parameter family of discrete isotropic Voss nets. This is a joint work with Helmut Pottman.
09 Jan 2023: Geometry seminar
Jan Gregorovic (TU Wien): Invariants of curves in conformal manifolds


I will talk about invariants that can be assigned to curves in conformal manifolds of dimension greater than 2. An invariant is a quantity depending only on the curve and the conformal class of metrics and in particular, is invariant under all conformal transformation. The construction of these invariants uses the description of conformal manifolds via tractor bundles, which I describe in detail. Using tractor fields instead of vector fields along the curve allows to construct an analogy of the Frenet frame and use it to define invariants.
28 Nov 2022: Geometry seminar
Günter Rote (FU Berlin): Grid peeling and the affine curve-shortening flow


Grid Peeling is the process of taking the integer grid points inside a convex region and repeatedly removing the convex hull vertices. It has been observed by Eppstein, Har-Peled, and Nivasch, that, as the grid is refined, this process converges to the Affine Curve-Shortening Flow (ACSF), which is defined as a deformation of a smooth curve.

As part of the M.Ed. thesis of Moritz Rüber, we have investigated the grid peeling process for special parabolas, and we could observe some striking phenomena. This has lead to a conjecture for the value of the constant that relates the two processes.

14 Nov 2022: Geometry seminar
Karoly Bezdek (University of Calgary): Ball polyhedra -- old and new


We survey a number of metric properties of intersections of finitely many congruent balls called ball polyhedra in Euclidean spaces. In particular, our talk is centered around the status of the shortest billiard conjecture, the global rigidity conjecture, Hadwiger???s covering conjecture, and the Gromov-Klee-Wagon volumetric conjecture for ball polyhedra.

17 Oct 2022: Geometry seminar
Group meeting

Events in former years

External Links

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