John Christian Ottem

Image of John Christian Ottem
Norwegian version of this page
Phone +47 22855930
Room 1109
Visiting address Moltke Moes vei 35 Niels Henrik Abels hus 0851 Oslo
Postal address Postboks 1053 Blindern 0316 Oslo

Personal webpage


Research interests

Higher dimensional algebraic geometry, positivity of line bundles and subschemes, Calabi-Yau manifolds, and the moduli space of curves.


'Young Research Talents'. Research Council of Norway 2016-2021.


This term I am teaching MAT1110 - Calculus and linear algebra and MAT4215 - Algebraic Geometry II.


Bernt Ivar Utstøl Nødland (2016-2019)
Bjørn Skauli (2018-)
Martin Helsø (2017-, co-advisor)
Elisa Cazzador (2018-, co-advisor)
Simen Westbye Moe (2019-)


  1. Two coniveau filtrations (with O. Benoist) (2020)
  2. Tropical degenerations and stable rationality (with J. Nicaise) (2019)
  3. A pencil of Enriques surfaces with non-algebraic integral Hodge classes (with F. Suzuki) Mathematische Annalen (to appear).
  4. On deformations of quintic and septic hypersurfaces (with S. Schreieder) Journal de Mathématiques Pures et Appliquées 135 (2020), 140-158.
  5. Remarks on the positivity of the cotangent bundle of a K3 surface (with F. Gounelas) (2018)
  6. Curve classes on irreducible holomorphic symplectic varieties (with G. Mongardi) Communications in Contemporary Mathematics (to appear)
  7. Failure of the integral Hodge conjecture for threefolds of Kodaira dimension zero (with O. Benoist). Commentarii Mathematici Helvetici (to appear)
  8. A counterexample to the birational Torelli problem for Calabi-Yau 3-folds (with J. V. Rennemo). Journal of the London Mathematical Society 97 (2018), 427-440
  9. Positivity of the diagonal (with B. Lehmann). Advances in Mathematics 335 (2018), 664-695.
  10. Effective cones of cycles on blow-ups of projective space (with I. Coskun, J. Lesieutre). Algebra & Number Theory 10-9 (2016).
  11. Nef cycles on some hyperkahler fourfolds. LMS volume for Fulton 80 (to appear)
  12. Curves disjoint from a nef divisor (with J. Lesieutre). Michigan Mathematical Journal 65 (2016), 321-332.
  13. On subvarieties with ample normal bundle. Journal of the European Mathematical Society 18 (2016), 2459-2468
  14. Birational geometry of hypersurfaces in products of projective spaces. Mathematische Zeitschrift 280 (2015), 135-148
  15. Partially ample line bundles on toric varieties. (with N. Broomhead and A. Prendergast-Smith). Glasgow Math. J. 58 (2016)
  16. Quartic spectrahedra (with K. Ranestad, B. Sturmfels, C. Vinzant) Mathematical Programming 151 (2), 585-612 (2015).
  17. Ample subvarieties and q-ample divisors. Advances in Mathematics 229 (2012), 2868-2887.
  18. Components of the Hilbert scheme of space curves on low-degree smooth surfaces (with J. O. Kleppe). International Journal of Mathematics Vol. 26, (2015)
  19. Algebraic boundaries of Hilbert's SOS cones (with G. Blekherman, J. Hauenstein, K. Ranestad and B. Sturmfels). Compositio Mathematica 148 (2012).
  20. The Cox ring of a K3 surface of Picard number two. Journal of Pure and Applied Algebra 217 (2013), 709-715.
  21. On the Cox Ring of P2 Blown Up in Points on a Line. Mathematica Scandinavica 9, (2011), 21-31.


Tags: Algebra and algebraic geometry
Published Jan. 6, 2016 9:05 AM - Last modified Apr. 9, 2021 8:22 AM