Department of Mathematics

University of Pennsylvania

Office: 4N61 David Rittenhouse Lab

Office Phone: 215-573-1029

Email: wibmer@math.upenn.edu

Mailing Address:

Department of Mathematics

David Rittenhouse Lab.

209 South 33rd Street

Philadelphia, PA 19104-6395

- Differential embedding problems over complex function fields, with Annette Bachmayr, David Harbater, Julia Hartmann , ArXiv:1610.09336
- Torsors for difference algebraic groups, with Annette Bachmayr, ArXiv:1607.07035
- Strongly étale difference algebras and Babbitt's decomposition, with I. Tomašić, ArXiv:1405.6603
- Affine difference algebraic groups, ArXiv:1405.6603

- Tannakian categories with semigroup actions, with A. Ovchinnikov, to appear in Canadian Journal of Mathematics, link, ArXiv:1403.3850
- Difference algebraic relations among solutions of linear differential equations, with L. Di Vizio and Ch. Hardouin, to appear in Journal of the Institute of Mathematics of Jussieu, link, ArXiv:1310.1289
- σ-Galois theory of linear difference equations, with A. Ovchinnikov, International Mathematics Research Notices 2015 (12), 3962-4018 link, ArXiv:1304.2649
- Skolem-Mahler-Lech type theorems and Picard-Vessiot theory, Journal of the European Mathematical Society, Vol. 17, Issue 3, 523-533, 2015, link, ArXiv:1203.1449
- Difference Galois theory of linear differential equations, with L. Di Vizio and Ch. Hardouin, Advances in Mathematics 260, 1-58, 2014, link, ArXiv:1302.7198
- An intrinsic characterization of Picard-Vessiot extensions, Journal of Algebra 408, 183-188, 2014, link, ArXiv:1205.1726
- A Chevalley theorem for difference equations, Mathematische Annalen, Vol. 354, Issue 4, 1369-1396, 2012, link, ArXiv:1010.5066
- Existence of ∂-parameterized Picard-Vessiot extensions over fields with algebraically closed constants, Journal of Algebra 361, 163-171, 2012, link, ArXiv:1104.3514
- On the Galois theory of strongly normal differential and difference extensions, Séminaires et Congrès 27, 221-240, 2012, link
- Gröbner bases for polynomial systems with parameters, with A. Montes, Journal of Symbolic Computation, Vol. 45, Issue 12, 1391-1425, 2010, link
- Leakage quantification of cryptographic operations, with D. Biswas and F. Kerschbaum, In OTM Conferences (1) 2010: 685-700, link
- Gröbner bases for families of affine or projective schemes, Journal of Symbolic Computation, Vol. 42, Issue 8, 803-834, 2007, link, ArXiv:0608019
- On the dimension of coinvariants of permutation representations, with L. Smith, Monatshefte für Mathematik 151, no. 1, 75-81, 2006, link
- On invariant relations between zeros of polynomials, with K. Girstmair and F. Pauer, Communications in Algebra 33, no. 7, 2157-2166, 2005, link

- Affine difference algebraic groups, Habilitation thesis, RWTH Aachen University, 2015, pdf
- Geometric difference Galois theory, PhD thesis Heidelberg, 2010, link, pdf

- Notes from an introductory course in difference algebra
- Video from the talk "Étale Difference Algebraic Groups" given in the meeting "Model Theory, Difference/Differential Equations and Applications" at Luminy, April 2015.
- Slides from the talk "Finiteness properties of difference algebraic groups" given at the 2014 AMS Spring Central Sectional Meeting in Lubbock, Special Session on Differential Algebra and Galois Theory.
- Slides from the talk "Galois theory of strongly normal differential and difference extensions" given at the Joint Mathematics Meeting 2012 in Boston, AMS Special Session "Differential Algebraic Geometry and Galois Theory (in memory of Jerald Kovacic)".

Workshop on Differential Galois Theory and Differential Algebraic Groups (Toronto, July 2017)

Special Session on the Computational theory of differential and difference equations at MACIS2015 (Berlin, November 2015)

DART VI and International Summer School on Mathematics Mechanization (Beijing, August 2015)

Special Session on Computational Differential and Difference Algebra at ACA 2015 (Kalamata, July 2015)

Workshop Differential Algebra and Galois Theory (Aachen, September 2014)