This week's discoveries: What is the shape of a knot?
A 15-minute lecture inviting the audience to understand knots by curving the space around it.
227 Seminar, Leiden
An exposition of Conway's theorem of rational tangles following Kauffman. The algebra of continued fractions can be mimicked by simple knotting operations on a pair of ropes. Underlying reason: Mapping class group of the 4-punctured sphere is the modular group.
Lecture on the geometry of rotations, with many hands-on exercises (older English version).
Lecture: a Random walk through number theory. About probabilistic heuristics in number theory.
I gave a series of lectures on G. Perelman's Ricci flow and his solution of the Poincaré conjecture in the context of discrete surfaces.
Together with Lisa Steverink and Marie-Beth van Egmond I organised the very first Dutch open Dots and Boxes championship at the University of Amsterdam.
Lecture on quadratic reciprocity
I presented a pretty simple proof of the quadratic reciprocity law at the the Leve de wiskunde 2013 event. Here is the presentation and a short note containing the actual proof (Dutch). The actual lecture can be watched here (mine is the third presentation)
Thesis defence dance performance
To convey the essence of my PhD thesis I gave a short dance demonstration.