Mathematisches Institut der Universität Bonn

Till Wehrhan

Hello there! I finished my PhD under the supervision of Prof. Stroppel on 09/12/2024. Then I was a post-doctoral researcher at University of Edinburgh until fall 2025. Now I am looking for new adventures in the fields of informations technology. On the right hand side you see a picture of the 25 year old me taken at Burg Are.

---

Contact:

Email:        twehrhan[at]ed.ac.uk

---

Research Interests:

Geometric representation theory, quantum groups, (equivariant) Schubert calculus, bow varieties, quantum cohomology.

---

Preprints/Publications:

• Existence and orthogonality of stable envelopes for bow varieties; joint with Catharina Stroppel; accepted in Bulletin of the London Mathematical Society.
• Chevalley-Monk formulas for bow varieties; ArXiv preprint.

---

Teaching:

• Tutor for Algebraic geometry I; Lecturer: Dr. Martin, Winter 2022.
• Coorganizer of a graduate seminar about bow varieties and 3d mirror symmetry; Summer 2022.
• Tutor for advanced algebra (crystals and canonical bases); Lecturer: Prof. Stroppel, Winter 2021.
• Tutor for Auslander-Reiten theory; Lecturer: Prof. Schröer, Summer 2021.
• Tutor for homological algebra; Lecturer: Prof. Schröer, Winter 2020.
• Tutor for representation theory of finite dimensional algebras; Lecturer: Prof. Schröer, Summer 2020.
• Tutor for modular forms; Lecturer: Prof. Blomer, Winter 2019.
• Tutor for the precourse in mathematics; Lecturer: Dr. Rieger, Summer 2019.
• Instructor of the repetition course in commutative algebra; Summer 2019.
• Tutor for commutative algebra; Lecturer: Dr. Heidersdorf, Summer 2019.
• Tutor for invariant theory and algebraic groups; Lecturer: Prof. Stroppel, Winter 2018.
• Tutor for the precourse in mathematics; Lecturer: Dr. Welter, Summer 2018.
• Tutor for the precourse in mathematics; Lecturer: Dr. Welter, Summer 2017.
• Tutor for calculus II; Lecturer: Prof. Niethammer, Summer 2017.

---

Selected Seminar and Conference Talks:

• Geometry, Algebra, and Theoretical Physics Seminars London, 03/2024.
• Paris Algebra Seminar Paris, 01/2024.
• Workshop in honor of Peter Littelmann Cologne, 12/2023.
• Schubert Seminar, Rutgers University (online) 11/2023.
• EGRET Seminar Edinburgh, 11/2023.
• Chevalley-Monk formulas for bow varieties; IMPRS Seminar, Bonn, 11/2023.
• Chevalley-Monk formulas for bow varieties; Thesisday of Prof. Stroppel's working group, Bonn, 01/2023.
• Rim hook rules in equivariant quantum Schubert calculus via Bethe and Clifford algebras; Seminar on methods in geometric representation theory, Chapel Hill, 09/2022.
• Carlsson-Okounkov operator; Seminar on algebraic geometry, Bonn, 07/2022.
• Diagrammatics of quiver Schur algebras; Seminar on representation theory, Bonn, 06/2022.
• Conjectural picture of 3d mirror symmetry; Seminar on bow varieties and 3d mirror symmetry, Bonn, 05/2022.
• Generalizations of Schubert calculus; Workshop on Curves and K3 surfaces (junior talk), Bonn, 05/2022.
• Torus actions on bow varieties; Seminar on bow varieties and 3d mirror symmetry, Bonn, 05/2022.
• Flag varieties and modular representation theory; IMPRS Seminar, Bonn, 04/2022.
• Quantum $K$-theory and $3d$ mirror symmetry for hypertoric varieties; ArXiv Seminar, Bonn, 01/2022.
• $K$-theoretic sheaf counting on threefolds; IMPRS Seminar, Bonn, 01/2022.
• Virtual localization formula (after Graber-Pandharipande); Seminar on algebraic geometry, Bonn, 12/2021.
• Yetter-Drinfeld modules and Frobenius algebras; Seminar on representation theory, Bonn, 11/2021.
• Operations on $D$-modules II; Reading group on mixed Hodge modules, Bonn, 10/2021.
• Operations on $D$-modules I; Reading group on mixed Hodge modules, Bonn, 10/2021.
• Stable envelopes and bow varieties; ArXiv Seminar, Bonn 07/2021.
• On curve counting and quantum groups; BIGS exhibition, Bonn 06/2021.
• Yang-Baxter algebra operation on the cohomology of Grassmannians; Thesisday of Prof. Stroppel's working group, Bonn 06/2021.
• Yang-Baxter equation: origins and connection to symmetric polynomials; IMPRS Seminar, Bonn 04/2021.
• Quantum cohomology of the Hilbert scheme of points in the plane; Seminar on algebraic geometry, Bonn 02/2021.
• From triply graded to $\mathfrak gl_N$-homology; Seminar on knot homology, Bonn 02/2021.
• Beauville decomposition of the Chow ring of abelian varieties; IMPRS Seminar, Bonn 01/2021.
• Quantum cohomology of Grassmannians; Seminar on algebraic geometry, Bonn 12/2020.
• Small quantum cohomology; Seminar on algebraic geometry, Bonn 12/2020.
• Gromov-Witten invariants and big quantum cohomology; Seminar on algebraic geometry, Bonn 11/2020.
• Exceptional collections for Grassmannians; Seminar on representation theory, Bonn 07/2020.
• Alternating quiver Hecke algebras; Master thesis talk, Bonn 06/2020.
• Hall-Algebra of $\mathbb F_1$ representations; Seminar on advanced algebra, Bonn 12/2019.
• FRT-construction and quantum groups; Seminar on algebraic geometry, Bonn 11/2019.
• Introduction to equivariant cohomology; Seminar on representation theory, Bonn 07/2019.
• Lines on projective surfaces; Seminar on representation theory, Bonn 06/2019.
• Structure theorems for Hopf algebras; Seminar on topology, Bonn 05/2019.
• Multilinear restriction estimate; Seminar on harmonic analysis, Bonn 11/2018.
• Hall algebras and quiver representations; Seminar on representation theory, Bonn 10/2018.
• The Steenrod algebra; Seminar on topology, Bonn 06/2018.

---

Theses:

• Representation theory of alternating nil Hecke algebras; Master thesis; Supervisor: Prof. Stroppel.
• Aspekte der Darstellungstheorie von $\operatorname{GL}_2(\mathbb F_q)$, $\operatorname{SL}_2(\mathbb F_q)$ und $\operatorname{GL}_2(\mathbb Q_p)$; Bachelor thesis; Supervisor: Prof. Stroppel.

If you are interested in my theses, please contact me via mail.