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The p 1 -central extension of the Mapping Class Group of orientable surfaces

Sylvain Gervais (1998)

Banach Center Publications

Topological Quantum Field Theories are closely related to representations of Mapping Class Groups of surfaces. Considering the case of the TQFTs derived from the Kauffman bracket, we describe the central extension coming from this representation, which is just a projective extension.

The Whitehead link, the Borromean rings and the knot 946 are universal.

Hugh M. Hilden, María Teresa Lozano, José María Montesinos (1983)

Collectanea Mathematica

A link L in S3 is universal if every closed, orientable 3-manifold is a covering of S3 branched over L. Thurston [1] proved that universal links exist and he asked if there is a universal knot, and also if the Whitehead link and the Figure-eight knot are universal. In [2], [3] we answered the first question by constructing a universal knot. The purpose of this paper is to prove that the Whitehead link and the Borromean rings, among others, are universal. The question about the Figure-eight knot...

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