Efficient triangulations and boundary slopes
Abstract
For a compact, irreducible, -irreducible, an-annular bounded 3-manifold , then any triangulation of can be modified to an ideal triangulation of . We use the inverse relationship of crushing a triangulation along a normal surface and that of inflating an ideal triangulation to introduce and study boundary-efficient triangulations and end-efficient ideal triangulations. We prove that the topological conditions necessary for a compact 3-manifold admitting an annular-efficient triangulation are sufficient to modify any triangulation of to a boundary-efficient triangulation which is also annular-efficient. From the proof we have for any ideal triangulation and any inflation , there is a bijective correspondence between the closed normal surfaces in and the closed normal surfaces in with corresponding normal surfaces being homeomorphic. It follows that for an ideal triangulation that is -efficient, -efficient, or end-efficient, then any inflation of is -efficient, -efficient, or -efficient, respectively. There are algorithms to decide if a given triangulation or ideal triangulation of a -manifold is one of these efficient triangulations. Finally, it is shown that for an annular-efficient triangulation, there are only a finite number of boundary slopes for normal surfaces of a bounded Euler characteristic; hence, in a compact, orientable, irreducible, -irreducible, and an-annular -manifold, there are only finitely many boundary slopes for incompressible and -incompressible surfaces of a bounded Euler characteristic.
Cite
@article{arxiv.2006.14701,
title = {Efficient triangulations and boundary slopes},
author = {Birch Bryant and William Jaco and J. Hyam Rubinstein},
journal= {arXiv preprint arXiv:2006.14701},
year = {2020}
}
Comments
21 pages, 6 figures; revised and improved version of an earlier paper arXiv:1108.2936, Annular efficient triangulations of 3-manifolds