Kalina Mincheva

Algebra and Combinatorics Seminar

We meet weekly on Wednesday at 3:00 PM (Central time), GI-126(A)

Organizers: Alessandra Constantini and Kalina Mincheva.

Fall 2026

September 9
  • Francesca Gandini, St. Olaf College.
    Combinatorial aspects of lattices associated to subspace arrangements arising from group actions. .
    Consider a finite group acting linearly on a vector space. Each group element can be represented as a linear map whose graph is a subspace and the collection of these graphs gives a subspace arrangement. From an algebraic point of view, the vanishing ideal of the union of the subspaces can be used to find generators for the ring of polynomial invariants under the action of the group. Geometrically, we can also study the intersection lattice of the subspace arrangement, which can give cohomological information about the same ideal.
    When one considers permutation actions, new combinatorial perspectives on this intersection lattice arise. In particular, for the regular action of the group on itself, the intersection lattice of the subspace arrangement is isomorphic to the coset poset, a known object of study in geometric and topological combinatorics. For other permutation actions, we establish that stabiliser subgroups of orbit partitions and their cosets can be used to label the vertices of the lattice. We then study these lattices with combinatorial techniques and computational tools to better understand the various algebraic structures associated with them.
September 16
  • Ngoc Trinh Le, Tulane University.
    Relations between higher level Hurwitz class numbers. .
    We connect generalizations of the classical Hurwitz class numbers coming from two different frameworks: one introduced by Pei and Wang, arising from the generalized Cohen--Eisenstein series, and another by Li, Skoruppa, and Zhou, arising from Eichler orders of quaternion algebras. As applications, we obtain new basis for Eisenstein space $E_{3/2}^{+}(4N,\mathrm{id})$, a generalization of recent results of Beckwith and Mono, and a generalization of Gauss' formula. This is joint work with Olivia Beckwith.
September 23
  • Victoria Schleis, Durham University, UK.
    TBA. .
    TBA
September 30
  • Aniketh Sivakumar, Tulane University.
    TBA. .
    TBA.
October 7
  • Alexander Heaton, Lawrence University.
    TBA. .
    TBA.
October 14
  • Alexandra Seceleanu, University Nebraska - Lincoln.
    TBA. .
    TBA.
October 21
  • Matthew Ortiz, University of North Texas.
    TBA. .
    TBA.
October 28
  • Lisa Seccia, University of Neuchâtel.
    TBA. .
    TBA.
November 11
  • William Newman, Ohio State University.
    TBA. .
    TBA.
November 18
  • Griffin Edwards, Georgia Tech.
    TBA. .
    TBA.
December 3
  • TBA.
    TBA. .
    TBA.

Past seminars.