### Impacto

Montesinos Amilibia, José María and González Acuña, Francisco Javier
(1983)
*Quasiaspherical knots with infinitely many ends.*
Commentarii Mathematici Helvetici , 58
(2).
pp. 257-263.
ISSN 0010-2571

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Official URL: http://www.springerlink.com/content/q3x151q700053g45/

## Abstract

A smooth n-knot K in Sn+2 is said to be quasiaspherical if Hn+1(U)=0, where U is the universal cover of the exterior of K. Let G be the group of K and H the subgroup generated by a meridian. Then (G,H) is said to be unsplittable if G does not have a free product with amalgamation decomposition A∗FB with F finite and H contained in A. The authors prove that K is quasiaspherical if and only if (G,H) is unsplittable. If the group of K has a finite number of ends, then K is quasiaspherical and it was conjectured by the reviewer [J. Pure Appl. Algebra 20 (1981), no. 3, 317–324; MR0604323 (82j:57019)] that the converse was true. The authors give a very nice and useful method of constructing knots in Sn+2 and apply this method to produce counterexamples to the conjecture.

Item Type: | Article |
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Uncontrolled Keywords: | quasiaspherical n-knot; knot group; free product with amalgamation over a finite group; HNN-extension over a finite subgroup; infinitely many ends |

Subjects: | Sciences > Mathematics > Topology |

ID Code: | 17190 |

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Deposited On: | 23 Nov 2012 11:59 |

Last Modified: | 23 Nov 2012 11:59 |

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