2015
Dec
02

# Topology & geometry: Pavel Paták (HUJI), "Homological non-embeddability and a qualitative topological Helly-type theorem"

11:00am to 12:45pm

## Location:

Ross building, Hebrew University (Seminar Room 70A)

Abstract: The classical theorem of Van Kampen and Flores states that the k-dimensional skeleton of (2k+2)-dimensional simplex cannot be embedded into R2k.
We present a version of this theorem for chain maps and as an application we prove a qualitative topological Helly-type theorem.
If we define the Helly number of a finite family of sets to be one if all sets in the family have a point in common and as the largest size of inclusion-minimal subfamily with empty intersection otherwise, the theorem can be stated as follows: