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The minimizing of the Nielsen root classes

Daciberg Gonçalves, Claudemir Aniz (2004)

Open Mathematics

Given a map f: X→Y and a Nielsen root class, there is a number associated to this root class, which is the minimal number of points among all root classes which are H-related to the given one for all homotopies H of the map f. We show that for maps between closed surfaces it is possible to deform f such that all the Nielsen root classes have cardinality equal to the minimal number if and only if either N R[f]≤1, or N R[f]>1 and f satisfies the Wecken property. Here N R[f] denotes the Nielsen...

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...

Two-fold branched coverings of S3 have type six.

Maria Rita Casali (1992)

Revista Matemática de la Universidad Complutense de Madrid

In this work, we prove that every closed, orientable 3-manifold M3 which is a two-fold covering of S3 branched over a link, has type six.

Uncountably many wild knots whose cyclic branched covering are S3.

José María Montesinos-Amilibia (2003)

Revista Matemática Complutense

There is a disk in S3 whose interior is PL embedded and whose boundary has a tame Cantor set of locally wild points, such that the n-fold cyclic coverings of S3 branched over the boundary of the disk are all S3. An uncountable set of inequivalent wild knots with these properties is exhibited.

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