The triangulation complexity of fibred 3-manifolds

Jessica Purcell (Monash)

Abstract: The triangulation complexity of a 3-manifold M is the minimal number of tetrahedra required to form a triangulation of M. It is a useful invariant, for example in computational topology, but surprisingly difficult to compute. We consider the case that M is a closed orientable hyperbolic 3-manifold that fibers over the circle. We show that the triangulation complexity of such a manifold is equal to the translation length of the monodromy action on the mapping class group of the fibre, up to a bounded factor depending only on the genus of the fibre. This is joint work with Marc Lackenby.