56 citations · 130 across the 13 of their papers we have counts for
20 papers
Homotopy ribbon concordance, Blanchfield pairings, and twisted Alexander polynomials
Stefan Friedl, Takahiro Kitayama, Lukas Lewark +2
We establish homotopy ribbon concordance obstructions coming from the Blanchfield form and Levine-Tristram signatures. Then, as an application of twisted Alexander polynomials, we…
Embedding spheres in knot traces
Peter Feller, Allison N. Miller, Matthias Nagel +3
The trace of -framed surgery on a knot in is a 4-manifold homotopy equivalent to the 2-sphere. We characterise when a generator of the second homotopy group of such a mani…
Twisted signatures of fibered knots
Anthony Conway, Matthias Nagel
This paper concerns twisted signature invariants of knots and 3-manifolds. In the fibered case, we reduce the computation of these invariants to the study of the intersection form…
A survey of the foundations of four-manifold theory in the topological category
Stefan Friedl, Matthias Nagel, Patrick Orson +1
This survey aims to provide a guide to the literature on topological 4-manifolds. Foundational theorems on 4-manifolds are stated, especially in the topological category. Precise r…
Stably slice disks of links
Anthony Conway, Matthias Nagel
We define the stabilizing number of a knot as the minimal number of connected summands required for to bound a nullh…
Triple linking numbers and surface systems
Christopher William Davis, Matthias Nagel, Patrick Orson +1
We give a refined value group for the collection of triple linking numbers of links in the 3-sphere. Given two links with the same pairwise linking numbers we show that they have t…
Concordance of knots in
Christopher W. Davis, Matthias Nagel, JungHwan Park +1
We establish a number of results about smooth and topological concordance of knots in . The winding number of a knot in is defined to be its class in…
Smooth and topological almost concordance
Matthias Nagel, Patrick Orson, JungHwan Park +1
We investigate the disparity between smooth and topological almost concordance of knots in general 3-manifolds Y. Almost concordance is defined by considering knots in Y modulo con…
Multivariable signatures, genus bounds and -solvable cobordisms
Anthony Conway, Matthias Nagel, Enrico Toffoli
We refine prior bounds on how the multivariable signature and the nullity of a link change under link cobordisms. The formula generalizes a series of results about the 4-genus havi…
Satellites and concordance of knots in 3-manifolds
Stefan Friedl, Matthias Nagel, Patrick Orson +1
Given a 3-manifold and a free homotopy class in , we investigate the set of topological concordance classes of knots in representing the given homotop…
Concordance invariance of Levine-Tristram signatures of links
Matthias Nagel, Mark Powell
We determine for which complex numbers on the unit circle the Levine-Tristram signature and the nullity give rise to link concordance invariants.
Concordance group of virtual knots
Hans U. Boden, Matthias Nagel
We study concordance of virtual knots. Our main result is that a classical knot K is virtually slice if and only if it is classically slice. From this we deduce that the concordanc…
Representation varieties detect essential surfaces
Stefan Friedl, Takahiro Kitayama, Matthias Nagel
Extending Culler-Shalen theory, Hara and the second author presented a way to construct certain kinds of branched surfaces in a -manifold from an ideal point of a curve in the $…
Twisted Blanchfield pairings and decompositions of 3-manifolds
Stefan Friedl, Constance Leidy, Matthias Nagel +1
We prove a decomposition formula for twisted Blanchfield pairings of 3-manifolds. As an application we show that the twisted Blanchfield pairing of a 3-manifold obtained from a 3-m…
A note on the existence of essential tribranched surfaces
Stefan Friedl, Takahiro Kitayama, Matthias Nagel
The second author and Hara introduced the notion of an essential tribranched surface that is a generalisation of the notion of an essential embedded surface in a 3-manifold. We sho…
Twisted Reidemeister torsion and the Thurston norm: graph manifolds and finite representations
Stefan Friedl, Matthias Nagel
We show that the Thurston norm of any irreducible 3-manifold can be detected using twisted Reidemeister torsions corresponding to integral representations and also corresponding to…
Unlinking information from 4-manifolds
Matthias Nagel, Brendan Owens
We generalise theorems of Cochran-Lickorish and Owens-Strle to the case of links with more than one component. This enables the use of linking forms on double branched covers, Heeg…
3-manifolds that can be made acyclic
Stefan Friedl, Matthias Nagel
We determine which 3-manifolds admit a unitary representation such that the corresponding twisted chain complex is acyclic.
A specious unlinking strategy
Stefan Friedl, Matthias Nagel, Mark Powell
We show that the following unlinking strategy does not always yield an optimal sequence of crossing changes: first split the link with the minimal number of crossing changes, and t…
Minimal genus in circle bundles over 3-manifolds
Matthias Nagel
An estimate for the genus function in circle bundles over irreducible 3-manifolds is proven. This estimate is in many cases an equality and it relates the minimal genus of the surf…