#### Volume 10, issue 2 (2010)

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The length of unknotting tunnels

### Daryl Cooper, Marc Lackenby and Jessica S Purcell

Algebraic & Geometric Topology 10 (2010) 637–661
##### Abstract

We show there exist tunnel number one hyperbolic $3$–manifolds with arbitrarily long unknotting tunnel. This provides a negative answer to an old question of Colin Adams.

##### Keywords
unknotting tunnel, hyperbolic $3$–manifold, geodesic
Primary: 57M50