Institute of
Discrete Mathematics and Geometry

Discrete Mathematics Working Group (Arbeitsgemeinschaft Diskrete Mathematik, AGDM)

Info: The AGDM seminar is a joint seminar of the University of Vienna and TU Wien. In winter semesters, we meet on Tuesdays from 15:00 to 16:30 at the University of Vienna. In summer semesters, we meet on Tuesdays at TU Wien.

Since 2025, we use a mailing-list to advertise the seminar. You can register here.

Place: TU Wien (Freihaus, Wiedner Hauptstr. 8-10, 1040 Wien): Room DA 08 B19 (Dissertantenzimmer), 8th floor, Tower A (green)

Time:Tuesday, 16:00-17:30

Next talk

Date: Tuesday 17.03.2026
Title: Moments of Pólya urns balanced in expectation
Speaker: Colin Desmarais (TU Wien)
Abstract: A generalized Pólya urn contains balls of different colours; at each step a ball is selected at random from the urn and replaced with a (potentially random) set of other balls, with the replacement rule depending only on the colour of the ball sampled at that step. Generalized Pólya urns have long been used to study properties of random trees; for example in proving joint normal limit laws for degrees in random recursive trees and other similar increasing trees. Recent works have proven that convergence of moments also holds for many cases of Pólya urns admitting normal limit laws. These results, however, often assume the urn is balanced; that is, the number of balls replaced at each step is constant.
In this talk, I will present new results for the convergence of moments for urns balanced in expectation, meaning that we only require that the expected number of balls replaced at each step is constant. I will also present applications of these results to the degree distributions of hooking networks and uniform attachment trees with freezing. In contrast with classical models of increasing trees, the urns associated with the vertices of these two recently introduced random networks are not balanced, but are balanced in expectation.

Code of conduct

Maintaining a respectful environment is essential to fostering meaningful dialogue and intellectual growth. Participants are expected to refrain from any form of disrespectful or inappropriate behaviour, including offensive comments, harassment, or disruptive conduct. Questions and contributions should be constructive, relevant to the topic, and posed in a professional manner that encourages healthy academic exchange. Harassment of any kind—including verbal, moral or physical—will not be tolerated, and all attendees are urged to uphold these principles to ensure a safe and welcoming atmosphere for everyone.

Upcoming talks

14.04.2026 Álvaro Gutiérrez Cáceres (University of Bristol)
28.04.2026Niccolò Bosio (TU Wien)
12.05.2026
26.05.2026Kalina Petrova (ISTA)

Talks in the past years

Talks of years 2005 - 2026

Past talks of this year

27.01.2026Mona Gatzweiler (University of Vienna)Kreweras words and the Cyclic Sieving Phenomenon
20.01.2026Markus Reibnegger (University of Vienna)Some combinatorial topics in $p$-adic representation theory
13.01.2026Abdulhafeez Abdulsalam (University of Vienna)Signed Generalized Stirling Polynomials and Generalized Hyperbolic Integrals
16.12.2025Atsuro Yoshida (University of Vienna)A Probabilistic Bijection from the Twenty-Vertex Model to Arrowed Gelfand-Tsetlin Patterns
09.12.2025Alin Bostan (INRIA, Sorbonne Université)On Deciding Transcendence of Power Series
09.12.2025Anastasia Matveeva (École polytechnique)On the Integrality of Some P-recursive Sequences
02.12.2025Marcus Schönfelder (University of Vienna)The $1/4$-phenomenon of placement probabilities of tilings in the Aztec diamond
25.11.2025Joshua Jeishing Wen (University of Vienna)Tesler identities for wreath Macdonald polynomials
18.11.2025Fabián Levicán (University of Vienna)Embeddings of weighted projective spaces
11.11.2025Nicolas Allen Smoot (University of Vienna)Some New Examples of Modular Congruence Multiplicities
04.11.2025Eva-Maria Hainzl (TU Wien)Functional equations with catalytic variable 101
28.10.2025Shane Chern (University of Vienna)The Koutschan-Krattenthaler-Schlosser determinants and their combinatorics
21.10.2025Sergio Alejandro Fernandez de Soto Guerrero (TU Graz)MathMagic: A positroidal action over a deck of cards
14.10.2025Christian Krattenthaler (University of Vienna)Two Topics, Four Lessons
07.10.2025Matija Bucic (University of Vienna)Equiangular lines via improved eigenvalue multiplicity