Combinatorial conditions that imply word-hyperbolicity for 3-manifolds
arXiv:math/0301057 · doi:10.1016/S0040-9383(02)00100-3
Abstract
Thurston conjectured that a closed triangulated 3-manifold in which every edge has degree 5 or 6, and no two edges of degree 5 lie in a common 2-cell, has word-hyperbolic fundamental group. We establish Thurston's conjecture by proving that such a manifold admits a piecewise Euclidean metric of non-positive curvature and the universal cover contains no isometrically embedded flat planes. The proof involves a mixture of computer computation and techniques from small cancellation theory.
(21 pages) To appear in Topology