Prof. Dr. Sebastian Hensel Mathematics Institute, University of Munich Theresienstr. 39 D-80333 Munich Germany Email: hensel@math.lmu.de Tel:   +49 (0)89   2180 4448 Office: room 318, 3rd floor Geometry and Topology Group

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About Me

Research

Teaching

Other

My research lies at the intersection of low-dimensional topology and geometric group theory. I mainly study algebraic and geometric properties of mapping class groups, handlebody groups and the spaces they act on. Recently I have been very interested in using methods from geometric group theory in the study of diffeomorphism groups of surfaces.

Preprints

• From curve graphs to fine curve graphs and back
  (joint with Federica Fanoni).
  

  • arXiv:2409.05647
• Towards the boundary of the fine curve graph
  (joint with Jonathan Bowden and Richard Webb).
  

  • arXiv:2402.18948
• Linear progress in fibres
  (joint with Vaibhav Gadre).
  

  • arXiv:2203.13557
• Multitwists in big mapping class groups
  (joint with Federica Fanoni and George Domat).
  

  • arXiv:2301.08780
• Measure equivalence rigidity of the handlebody groups
  (joint with Camille Horbez).
  

  • arXiv:2111.10064
• Rigidity of the Torelli subgroup in Out(F_N)
  (joint with Camille Horbez and Ric Wade).
  

  • PDF
  • arXiv:1910.10189
• Path-connectivity of the set of uniquely ergodic and cobounded foliations
  (Joint with Jon Chaika)
  

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  • arXiv:1909.03668
• Homological Approximations to the Handlebody Group
  

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Short notes

• Out(F_n) does not lift to the handlebody group
  

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Published Articles

• Strong Haken via Sphere Complexes
  (joint with Jennifer Schultens).
  Algebraic and Geometric Topology 24-5 (2024), 2707--2719.

  • PDF
  • arXiv:2102.09831
  • Journal
• Connectivity of the Gromov Boundary of the Free Factor Complex
  (joint with Mladen Bestvina and Jon Chaika).
  Annales Henri Lebesgue, Volume 6 (2023), pp. 1291-1348.

  • arXiv:2105.01537
  • Journal
• A projection from filling currents to Teichmüller space
  (joint with Jenya Sapir).
  Proc. Amer. Math. Soc. 151 (2023), 3621-3633

  • arXiv:2109.14768
  • PDF
  • Journal
• Rotation sets and actions on curves
  (joint with Jonathan Bowden, Kathryn Mann, Emmanuel Militon, and Richard Webb).
  Advances in Mathematics, Volume 408, Part B, 2022.
  

  • arXiv:2104.11217
  • Journal Version
• Big mapping class groups acting on homology
  (joint with Federica Fanoni and Nick Vlamis).
  Indiana University Mathematics Journal 70 (2021), no. 6, 2261–2294

  • PDF
  • arXiv:1905.12509
  • Journal Version
• Foliations from left orders
  (joint with Hyungryul Baik and Chenxi Wu).
  J. Korean Math. Soc. 2022; 59(4): 699-715
  

  • arXiv:2108.09694
  • Journal Version
• Handlebody Bundles and Polytopes
  (joint with Dawid Kielak).
  Algebraic and Geometric Topology 21-7 (2021), 3445-3458
  

  • PDF
  • arXiv:1904.08813
  • Journal Version
• Quasi-morphisms on surface diffeomorphism groups
  (joint with Jonathan Bowden and Richard Webb).
  Journal of the American Mathematical Society, Volume 35 (2022), 211-231.
  

  • PDF
  • arXiv:1909.07164
  • Journal Version
• The geometry of the handlebody groups II: Dehn functions
  (joint with Ursula Hamenstädt)
  Michigan Mathematical Journal, 70 (2021), 23-53
  

  • Published Version
  • PDF
  • arXiv:1804.11133
• (Un)distorted stabilisers in the handlebody group
  Journal of Topology, Volume 14, Issue 2, June 2021, pp. 460--487.
  

  • Journal Version (Open Access)
• A Primer on Handlebody Groups
  Appeared in the Handbook of Group Actions V
  

  • Published Version
  • PDF
• The set of uniquely ergodic IETs is path-connected
  (joint with Jon Chaika)
  Ergodic Theory and Dynamical Systems, Volume 39, Issue 2 February 2019, pp. 311-356.

  • PDF
  • SAGE code
  • arXiv:1405.0767
  • Journal Version
• Rigidity and Flexibility for Handlebody Groups
  Commentarii Mathematici Helvetici, Volume 93, Issue 2, 2018, pp. 335--358
  

  • PDF
  • arXiv:1608.03094
  • Published Version
• Exponential Torsion Growth for Random 3-Manifolds
  (joint with Hyungryul Baik, David Bauer, Ilya Gekhtman, Ursula Hamenstädt, Thorben Kastenholz, Bram Petri, Daniel Valenzuela)
  International Mathematics Research Notices, Vol. 2018, Issue 21, 2018, pp. 6497-6534

  • Journal Version
• Nielsen realisation for untwisted automorphisms of right‐angled Artin groups
  (joint with Dawid Kielak)
  Proceeding of the London Mathematical Society, Vol. 117, Issue 5, 2018, pp. 901--950.

  • PDF (old version)
  • arXiv:1410.1618
  • Journal Version
• Stability in Outer Space
  (joint with Ursula Hamenstädt)
  Groups, Geometry, and Dynamics, Vol. 12, Issue 1, 2018, pp. 359-398.

  • PDF
  • arXiv:1411.2281
  • Journal Version
• Relative Nielsen Realisation by Gluing: Limit Groups and Free Products
  (joint with Dawid Kielak)
  Michigan Journal of Mathematics, Vol. 67, Issue 1 (2018), pp.199--223.

  • PDF
  • arXiv:1601.02187
  • Journal Version
• Moving homology classes in finite covers of graphs
  (joint with Benson Farb)
  Israel Journal of Mathematics, Vol. 220, Issue 2 (2017), pp. 605-615

  • PDF
  • arXiv:1509.09253
  • Journal Version
• Finite covers of graphs, their primitive homology, and representation theory
  (joint with Benson Farb)
  New York Journal of Mathematics, Volume 22 (2016) 1365-1391

  • PDF
  • arXiv:1610.08819
  • Journal Version
• 1-slim triangles and uniform hyperbolicity for arc and curve graphs
  (joint with Piotr Przytycki and Richard Webb)
  Journal of the European Mathematical Society, Volume 17, Issue 4 (2015).

  • PDF
  • arXiv:1301.5577
  • Journal Version
• Realisation and dismantlability
  (joint with Damian Osajda and Piotr Przytycki)
  Geometry and Topology, Volume 18, Issue 4 (2014).

  • PDF
  • arXiv:1205.0513
  • Journal Version
• Isoperimetric inequalities for the handlebody groups
  (joint with Ursula Hamenstädt)
  Transactions of the American Mathematical Society 365 (2013).

  • PDF
  • arXiv:1109.5255
  • Journal Version
• Spheres and projections for Out(F_n)
  (joint with Ursula Hamenstädt)
  Journal of Topology 8 (2015).

  • PDF
  • arXiv:1109.2687
  • Journal Version
• The geometry of the handlebody groups I: Distortion
  (joint with Ursula Hamenstädt)
  Journal of Topology and Analysis, Volume 4, Issue 1 (2012).

  • PDF
  • arXiv:1101.1838
  • Journal Version
• The ending lamination space of the five-punctured sphere is the Nöbeling curve
  (joint with Piotr Przytycki)
  London Math. Soc. 84 (1) (2011).

  • PDF
  • arXiv:0910.3554
  • Journal Version
• Iterated Grafting and Holonomy Lifts of Teichmüller space
  Geometriae Dedicata Volume 155, Number 1 (2011)

  • PDF
  • arXiv:0802.3290
  • Journal Version

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