Wintersemester 2016/17
Freitag, 10:30-11:30, Seminarraum 2 (Raum 204)
18.11.16 | Matthias Nagel (Montréal, z.Zt. HIM Bonn) Concordance invariance of Levine-Tristram signatures of links Abstract: We determine for which complex numbers on the unit circle the Levine-Tristram signature gives rise to link concordance invariants. For this we recast the Levine-Tristram signature as a signature defect and use Cohn localization. This is joint work with Mark Powell. |
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9.12.16 | Thomas Rot (Köln) Classification of homotopy classes of Fredholm maps |
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16.12.16 | Christian Lange (Köln) Topology of complex hyperplane complements |
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27.1.17 | Sinem Onaran (Ankara) Legendrian Lens Space Surgeries Abstract: In this talk, first I will review topological Dehn surgery and its contact analogue, contact surgery. Then I will focus on a question: which tight contact structures on a given lens space can be obtained by a single contact (− 1)-surgery along a Legendrian knot in S^{3} with some contact structure? I will given an answer to the question for lens spaces L(ns^{2} − s + 1, s^{2}) with n ≥ 2, s ≥ 1. This work is joint with H. Geiges. |
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10.2.17 | Gerrit Herrmann (Regensburg) The L^{2}-Alexander torsion for Seifert fibre spaces Abstract: Dubois, Friedl and Lück define the L^{2}-Alexander torsion of a 3-manifold. It is a function τ^{(2)}(N,φ)(t) associated to a pair (N,φ), where N is an irreducible 3-manifold and φ is a first cohomology class. I calculate the L^{2}-Alexander torsion for Seifert fibre spaces and graph manifolds in terms of the Thurston norm. |
H. Geiges, 5.4.02