Spotted at the University of Vienna. Very impressive list from a perspective of discrete geometry, with the names of two of the most fundamental theorems (Radon and Helly) appearing.
Patrick Schnider
@schnpatr.bsky.social
Mathematician/Computer Scientist interested in discrete and computational geometry and topology. Working at University of Basel and ETH Zürich. https://people.inf.ethz.ch/schnpatr/
Day 2 of #FoCM26. A nice plenary talk by Beatrice Acciaio about the space of models for discrete stochastic processes. I don‘t know a lot about this, but still found the examples very interesting.
Other highlights of day 1 of #FoCM26: the second plenary talk was by Arno Kuilaars on (among other things) random tilings of hexagons, which lead to some fascinating effects and very pretty pictures.
Spending a few days in Vienna at #FoCM26. Looking forward to a hopefully very interesting conference.
I recently learned that my research was featured in an article in the Süddeutsche Zeitung on math for cutting pizzas www.sueddeutsche.de/projekte/art... It‘s unfortunately paywalled, if you want a copy dm me :)
Wie man mit Mathematik eine Pizza aufteilt
So teilt man Essen gerecht, auch wenn die Esser unterschiedliche Dinge mögen – oder im Hyperraum unterwegs sind.
sueddeutsche.de
Spending a week in beautiful Wergenstein for our workshop „Combinatorial, Topological and Algorithmic Aspects of Tverberg‘s Theorem“
Progress on one of my favorite problems: Langerman‘s conjecture states that any nd mass distributions in d-space can be simultaneously bisected by n hyperplanes. Pablo Soberon just informed me that he and Alfredo Hubard found 6 masses in 3-space that cannot be bisected by 2 planes!
5-year postdoctoral research fellowship in theoretical Computer Science (also 4 other research fields), a nice opportunity! Needs PhD to be awarded between 1/Aug/24 and 1/Oct/27. Please share with whoever may be suitable! www.asc.ox.ac.uk/post-doctora...
Post-Doctoral Research Fellowships | All Souls College
asc.ox.ac.uk
A question that stomped quite a few of my students: consider an naive version of the union find data structure (that is, without ranking or path compression). Given elements 0,1,2,3,4,5, what is a sequence of calls to union such that after the calls the representative tree is a path with root 0?
"I haven't really seen further than others, but they were looking in another direction." Academic tip: we're not all Newtons, and that's completely OK! You don't need to be a genius to do good research.
A few weeks ago I gave a talk at the New York Geometry Seminar about the alpha-Ham-Sandwich theorem. The talk is now online on YouTube: m.youtube.com/watch?v=MEiq...
Patrick Schnider: The alpha-Ham-Sandwich Theorem revisited
YouTube video by Computational Geometry
m.youtube.com
If you want to know a bit more about my recent paper with Juan, Ernst and Bastian, watch this video of Juan explaining it :)
Bastian Grossenbacher-Rieck@pseudomanifold.topology.rocks · 3mo agoA huge LEAP forward for graph learning and topological deep learning: Juan is taking about our recent ICLR work on learnable positional encodings. #MachineLearning #ICLR2026 🎥: youtu.be/7aniG7esPWU... 📝: openreview.net/forum?id=8XF...
A new paper on the #arXiv: with Daniel, Henry, Fabian, Irene and Birgit we study piercing double wedges (which in the primal corresponds to finding lines intersecting some segments and avoiding some others). We give algorithms but also Gallai-type combinatorial results. arxiv.org/abs/2604.23330
Bowties and Hourglasses: Intersections of Double-Wedges (or Stabbing and Avoiding Line Segments)
We study the common intersection of arrangements of double-wedges. We consider arrangements where double-wedges may be either bowties (which do not contain a vertical line) or hourglasses (which conta...
arxiv.org
Prof. Susanna Zimmermann has been invited to speak at the International Congress of Mathematicians — a major honour. First woman from the University of Basel. A specialist in algebraic geometry. dmi.unibas.ch/en/news-even... #ICM2026 #Mathematics #UniBasel
A special treat for the students in my course „Introduction to Topological Data Analysis“: Bastian Rieck (@pseudomanifold.topology.rocks) gave a very interesting guest lecture on topological methods in deep learning.
Very nice explanation of one of my favorite theorems in math, the Ham Sandwich theorem, by @manonym025.bsky.social www.scientificamerican.com/article/the-...
The mathematically correct way to slice a pizza
The intermediate value theorem shows us how to find an even center on an irregular shape
scientificamerican.com
🔗 Full materials: sites.google.com/site/thsaran...
Thatchaphol Saranurak - Graph Decomposition
What is this course about? This course studies modern graph algorithms through the lens of graph decomposition. Over the last two decades, expander decompositions and hierarchies have become some of ...
sites.google.com
Day 3 of #EuroCG26 started with an invited talk by Jean Cardinal on compact representations of graphs, where he particularly focused on biclique covers. An interesting topic I did not know about before.
Highlights from day 2 of #EuroCG26. The day started again with an invited talk, today by Maike Buchin who took us on a tour of 35 years of Frechét distance. A very interesting talk, and lots of great illustrations of dogs on walks.
Some personal highlights from day 1 of #EuroCG26: the day started with a great invited talk by Marcus Schaefer about penny graphs and the existential theory of the reals. I recently worked quite a bit in ETR, and it was very interesting to hear one of the founding fathers.
I am at #EuroCG26 in Hagen this week. It is once again an amazing conference with lots of interesting talks and discussions. There are also some of my MSc students from ETH here, attending their first ever conference, and it‘s great to see how they are welcomed by the CG community.
Very cool question with an elegant solution that I also discussed last week in my lecture (I‘m not going to say which lecture so as not to give hints about the answer) ☺️
Clément Canonne@ccanonne.github.io · 5mo agoA seemingly simple 🧩: let G be an arbitrary undirected (simple) graph on n vertices. Does G always have a cut with at least half its edges?
Spending an interesting week at Schloss Dagstuhl at the workshop „Intractability in Discrete Geometry and Topology“. A very nice venue, some cool open problems, and even cooler participants. www.dagstuhl.de/seminars/sem...
Last semester, I organised „Projects in Topological Data Analysis“, where students from several universities collaborate on problems in TDA. My Students Jette and Kalani, together with their mentors Anna and Tim have just uploaded their findings from their project to ArXiv: arxiv.org/abs/2603.07809
Which Vertical Graphs are Non VPHT Reconstructible?
The verbose persistent homology transform (VPHT) is a topological summary of shapes in Euclidean space. Assuming general position, the VPHT is injective, meaning shapes can be reconstructed using only...
arxiv.org
📚 New in arXiv cs.CG: Garment numbers of bi-colored point sets in the plane
Garment numbers of bi-colored point sets in the plane
New paper in cs.CG (Computational Geometry)
arxiv.org
A new paper on the ArXiv. This one is a result of the research week on geometric graphs in Trier in August 2024. Together with my coauthors Oswin, Helena, Niko, Maarten and Pepa we study a variant of the empty monochromatic quadrilateral problem. arxiv.org/abs/2603.05339 This will be at #EuroCG26
Garment numbers of bi-colored point sets in the plane
We consider colored variants of a class of geometric-combinatorial questions on $k$-gons and empty $k$-gons that have been started around 1935 by Erdős and Szekeres. In our setting we have $n$ points ...
arxiv.org
The list of accepted papers at #SoCG26 is now online: cgweek26.computational-geometry.org/contribute/
CG Week 2026
cgweek26.computational-geometry.org