Two varieties of tunnel number subadditivity

Knot theory and 3-manifold topology are closely intertwined, and few invariants stand so firmly in the intersection of these two subjects as the tunnel number of a knot, denoted t(K). We describe two very general constructions that result in knot and link pairs which are subbaditive with respect to...

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Bibliographic Details
Main Author: Schirmer, Trenton Frederick
Other Authors: Tomova, Maggy
Format: Others
Language:English
Published: University of Iowa 2012
Subjects:
Online Access:https://ir.uiowa.edu/etd/3379
https://ir.uiowa.edu/cgi/viewcontent.cgi?article=3324&context=etd
Description
Summary:Knot theory and 3-manifold topology are closely intertwined, and few invariants stand so firmly in the intersection of these two subjects as the tunnel number of a knot, denoted t(K). We describe two very general constructions that result in knot and link pairs which are subbaditive with respect to tunnel number under connect sum. Our constructions encompass all previously known examples and introduce many new ones. As an application we describe a class of knots K in the 3-sphere such that, for every manifold M obtained from an integral Dehn filling of E(K), g(E(K))>g(M).