Online Fernklausuren in Mathematik

Im letzten Semester mussten aufgrund der Pandemie viele Prüfungen in anderen (oft digitalen) Formaten abgehalten werden. Für das laufende Sommersemester – auch wenn sich die Lage derzeit bessert – scheint es mir wahrscheinlich, dass zumindest Prüfungen mit vielen Teilnehmern weiterhin Einschränkungen unterworfen sind. Daher will ich die Gelegenheit nutzen, um ein paar Überlegungen zu sammeln, … Continue reading "Online Fernklausuren in Mathematik"

Topological complexity

Rummaging in the arXiv I ran across this article and the notion of topological complexity which is really appealing. The idea of topological complexity isn’t quite new, it was developed by M. Farber in a short article published in 2003 in Discrete & Computational Geometry. The article doesn’t even have a proper review on MathSciNet, … Continue reading "Topological complexity"

The group of germs at infinity of line homeomorphisms

Recently, I learned that the group G∞ of germs at +∞ of orientation preserving homeomorphisms of the real line has two remarkable properites: it is simple and left-orderable. I thought it is maybe worth to share some background on left-orderability (and why this might be interesting). Let’s start with a definition: A group G is … Continue reading "The group of germs at infinity of line homeomorphisms"