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: University of Vienna, Faculty of Mathematics, Oskar-Morgenstern-Platz 1, BZ02, 2. Stock (2nd floor)
Time:Tuesday, 15:00-16:30
| Date: | Tuesday 10.11.2026 |
| Title: | The Differential Kernel Method: From Affine Motzkin Paths to Relaxed Binary Trees |
| Speaker: | Alexander Omelchenko (Constructor University Bremen) |
| Abstract: | The classical kernel method eliminates an unknown boundary generating function by evaluating a functional equation at a suitable root of its kernel. For height-dependent path models, the catalytic equation may instead become differential in the height variable, so that no algebraic kernel root is available. A differential analogue of kernel cancellation, based on integration along characteristics, will be presented. The method will first be illustrated on affine weighted Motzkin paths, where it leads to an Abel–Volterra equation for the return series and, in special cases, to explicit factorisations of the height-refined generating function. In the second part, joint work with Michael Wallner, the same mechanism will be applied to relaxed binary trees. In this case a returning characteristic produces a scalar Volterra equation for the diagonal generating function. It will also be shown how the critical characteristic geometry at a critical point leads naturally to the Airy function and to the asymptotic behaviour of the counting sequence. |
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.
| 24.11.2026 | Juanjo Rué | |
| 15.12.2026 | Marcus Schönfelder (Uni Wien) | |
| 12.01.2027 | Francesca Zaffalon (Max-Planck Institute) | |
| 26.01.2027 | Hans Höngesberg (Uni Wien) |
| 20.10.2026 | Hyunwoo Lee (KAIST) | Tower heights for color-avoiding Ramsey numbers of monotone paths |