Stefan Friedl

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We classify the metabelian unitary representations of π1(MK), where MK is the result of zero-surgery along a knot K ⊂ S. We show that certain eta invariants associated to metabelian representations π1(MK) → U(k) vanish for slice knots and that even more eta invariants vanish for ribbon knots and doubly slice knots. We show that this result contains the(More)
We show that given any 3-manifold N and any non-fibered class in H 1(N;Z) there exists a representation such that the corresponding twisted Alexander polynomial is zero. We obtain this result by extending earlier work of ours and by combining this with recent results of Agol and Wise on separability of 3-manifold groups. This result allows us to completely(More)
Every element in the first cohomology group of a 3–manifold is dual to embedded surfaces. The Thurston norm measures the minimal ‘complexity’ of such surfaces. For instance the Thurston norm of a knot complement determines the genus of the knot in the 3–sphere. We show that the degrees of twisted Alexander polynomials give lower bounds on the Thurston norm,(More)
In the early 1980’s Mike Freedman showed that all knots with trivial Alexander polynomial are topologically slice (with fundamental group Z). This paper contains the first new examples of topologically slice knots. In fact, we give a sufficient homological condition under which a knot is slice with fundamental group Z ⋉ Z[1/2]. These two fundamental groups(More)
We give a short introduction to the theory of twisted Alexander polynomials of a 3–manifold associated to a representation of its fundamental group. We summarize their formal properties and we explain their relationship to twisted Reidemeister torsion. We then give a survey of the many applications of twisted invariants to the study of topological problems.(More)
Let N be a closed, oriented 3–manifold. A folklore conjecture states that S× N admits a symplectic structure only if N admits a fibration over the circle. The purpose of this paper is to provide evidence to this conjecture studying suitable twisted Alexander polynomials of N , and showing that their behavior is the same as of those of fibered 3– manifolds.(More)