Jens Forsgård
Post-doctorant, Université de Genève.

Université de Genève
Mathématiques
Villa Battelle
1227 Carouge, Suisse
E-mail: Jens.Forsgaard -at- unige.ch

Photos taken by Elis Forsgård, Lionel Lang, and Hilary Page.

My CV is available here.

Last updated on 14 October 2017.

                             

Research
I am interested in geometry of zeros, tropical geomtry and (co)amoebas, toric geometry and polytopes, and A-hypergeometric functions.

I am currently a Post-doctorant (Postdoctoral Scholar) at Université de Genève, where my mentor is Professor Grigory Mikhalkin. Before, I was a Visiting Assistant Professor at Texas A&M University, mentored by Professor Laura Felicia Matusevich. I obtained my Ph.D. at Stockholm University under the supervision of Professor Boris Shapiro. I was a student of Mikael Passare at the time of his death.

                                

Recent preprints
  1. The Lattice of Amoebas, with T. de Wolff arXiv:1711.02705.

  2. Defective dual varieties for real spectra, to appear in Journal of Algebraic Combinatorics, arXiv:1710.02434.

  3. New subexponential fewnomial hypersurface bounds, with M. Nisse and J. Maurice Rojas, arXiv:1710.00481.

  4. On transformations of A-hypergeometric functions, with L. F. Matusevich and A. Sobieska, to appear in Funkcialaj Ekvacioj, arXiv:1703.03036.

  5. On the multivariate Fujiwara bound for exponential sums, submitted, arXiv:1612.03738.

  6. Lopsided amoeba approximation, with L. F. Matusevich, N. Mehlhop, and T. de Wolff, to appear in Mathematics of Computation, arXiv:1608.08663. (An implementation can be found here.)

  7. On dimer models and coamoebas, to appear in Ann. Inst. Henri Poincaré D, arXiv:1602.01826.

  8. Discriminant amoebas and lopsidedness, to appear in Journal of Commutative Algebra.
                             

Published Papers
In reverse chronological order.
  1. Coamoebas of polynomials supported on circuits, in Analysis Meets Geometry, The Mikael Passare Memorial Volume (Andersson, Boman, Kiselman, Kurasov, and Sigurdsson, eds.), Trends in Mathematics, Birkhäuser, Basel, 2017, pp. 191–212, doi:10.1007/978-3-319-52471-9_13, arXiv:1601.05468.

  2. On the parametric behavior of A-hypergeometric series, with C. Berkesch Zamaere and L. F. Matusevich, Trans. Amer. Math. Soc., in press, doi:10.1090/tran/7071, arXiv:1603.08954.

  3. A tropical analog of Descartes' rule of signs, with D. Novikov and B. Shapiro, Int. Math. Res. Notices 2017 (2017), no. 12, 3726–3750, doi:10.1093/imrn/rnw118, arXiv:1510.03257.

  4. Hypergeometric functions for projective toric curves, with C. Berkesch Zamaere and L. F. Matusevich, Adv. Math. 300 (2016), 835–867, doi:10.1016/j.aim.2016.03.032, arXiv:1412.3957.

  5. Could Renè Descartes have known this?, with B. Shapiro and V. P. Kostov, Exp. Math. 24 (2015), no. 4, 438–448, doi:10.1080/10586458.2015.1030051, arXiv:1501.00856. (1501_Descartes.nb.)

  6. On the order map for hypersurface coamoebas, with P. Johansson, Ark. Mat. 53 (2015), no. 1, 79–104, doi:10.1007/s11512-013-0195-y, arXiv:1205.2014.

  7. Coamoebas and line arrangements in dimension two, with P. Johansson, Math. Z. 278 (2014), no. 1–2, 25–38, doi:10.1007/s00209-014-1303-9.

  8. Euler–Mellin integrals and A-hypergeometric functions, with C. Berkesch and M. Passare, Michigan Math. J. 63 (2014), no. 1, 101–123, doi:10.1307/mmj/1395234361, arXiv:1103.6273.
                             

Other publications
  1. Coamoebas of bivariate multi-affine polynomials.

  2. Rullgård's wild guess is false.

  3. A Mathematica notebook for drawing coamoebas is available here.

  4. Tropical aspects of real polynomials and hypergeometric functions, doctoral thesis, Stockholm University, 2015. Available here.

  5. On hypersurface coamoebas and integral representations of A-hypergeometric functions, licentiate thesis, Stockholm University, 2012. Available here.
                             

Previous affiliations