Speaker: Jonathan Spreer, University of Sydney

Date: Feb 24, 2021

Time: 3:30 PM

Room: Virtual

Abstract: Many fundamental topological problems about 3-manifolds are algorithmically

solvable in theory but continue to withstand practical computations. In recent years some

of these problems have been shown to allow efficient solutions, if the input 3-manifold comes with a sufficiently ”thin” presentation.

More specifically, a 3-manifold given as a triangulation is considered thin, if the

treewidth of its dual graph is small. I will show how this combinatorial parameter, defined

on a triangulation, can be linked back to purely topological properties of the underlying

manifold. From this connection it can then be followed that, for some 3-manifolds, we

cannot hope for a thin triangulation.

Also, for any Australians stopping by (including the speaker), the talk  is Thursday, 8:30AM AEDT