SPP 2026 – Page 2 – Geometry at Infinity

Progress on the union-closed sets conjecture

The union-closed sets conjecture is the following extremely easy to state conjecture about subsets of finite sets: Assume that \(\mathcal{F}\) is a family of subsets of \(\{1, 2, \ldots, n\}\) which is union-closed; this means that for any two sets \(A,B\) in \(\mathcal{F}\) their union \(A \cup B\) is also a member of \(\mathcal{F}\). Then … Continue reading

Status-Bias im Peer-Review

In der aktuellen Forschung & Lehre ist ein Beitrag mit dem Titel Status-Bias im Peer-Review-Verfahren, den ich sehr interessant fand. Der Beitrag beginnt mit folgenden Worten: Forschungsarbeiten von renommierten Wissenschaftlerinnen und Wissenschaftlern werden trotz gleicher Qualität im Peer-Review-Verfahren deutlich besser bewertet als Arbeiten weniger bekannter Forschender. Zu diesem Ergebnis kommt ein Wissenschaftlerteam um Professor Jürgen … Continue reading

Conjectures about polynomials

Recently I stumbled upon the following two conjectures about polynomials: The first one is the Jacobian conjecture: We have polynomials \(f_1, \ldots, f_n\) in the variables \(x_1, \ldots, x_n\) with coefficients in a field \(k\) of non-zero characteristic. We define a function \(F\colon k^n \to k^n\) by setting \[F(x_1, \ldots, x_n) := (f_1(x_1, \ldots, x_n), … Continue reading

Non-positive immersions

In a blog post about hyperbolicity of one-relator groups I mentioned the following property that a 2-dimensional complex \(X\) might have: \(X\) is said to have non-positive immersions if for every immersion of a finite, connected 2-complex \(Y\) into \(X\), we either have \(\chi(Y) \le 0\) or \(Y\) is contractible. For example, this property rules … Continue reading

Announcing a result on the arXiv

Today Rachel Greenfeld and Terence Tao announced via the arXiv that they can disprove the periodic tiling conjecture (arXiv:2209.08451). I do not want to discuss here in detail the contents of the conjecture or their approach to disprove it (if you are interested in this, you can read about it on Tao’s blog). What I … Continue reading

Predicting the future of arbitrary functions

Let \(S\) be any non-empty set. If you have a function \(f\colon \mathbb{R} \to S\) and you tell me its values on an interval \((-\infty,t)\), can I predict which value it will have at the time \(t\)? If the function is continuous, then of course I can; and in general not. Now interestingly, if you … Continue reading

Fields medalists 2022

Recently the Fields medalists 2022 (and all the other prizes given out by the IMU) were announced: official page. You can read about some of the achievements of these people on the blog of Gil Kalai (and of course also in the official laudationes).

Shaw Prize 2022

The Shaw Prize in Mathematical Sciences 2022 (link) is awarded to Noga Alon and to Ehud Hrushovski for their remarkable contributions to discrete mathematics and model theory with interaction notably with algebraic geometry, topology and computer sciences.