Dear colleagues,

let me invite you to the next session of our doctoral seminar that will take place tomorrow at 9:50 in S6 (please note the "unusual" starting time). I will present a paper entitled "Borel Circle Squaring" by Andrew S. Marks and Spencer T. Unger [1].

The paper shows how to cut a unit circle in the plane into a finite number of Borel sets, so that translated copies of these sets form a unit square. I will show how to transform this problem into a question about existence of integral flows in infinite graphs. Then I will show, in analogy to the Ford-Fulkerson theorem, how to round a real-valued flow in an infinite graph to an integral flow. And, as a last step, I would like to describe an explicit construction of a certain real-valued flow that will then imply that "a circle can be squared".

Looking forward to seeing you all tomorrow,

Vojta

[1] https://arxiv.org/abs/1612.05833