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NDSU Mathematics


Fall 2022 Mathematics Colloquium

Time and Location:

Minard 112 at 3:00 PM (Refreshments at 2:30 in Minard 404)

Special Colloquia or Tri-College Colloquia venues and times may vary, please consult the individual listing.

Tuesday, October 11             Oliver Pechenik (University of Waterloo)

Cell decompositions and rings-with-bases

Abstract: When I first saw linear algebra, every vector space was $\mathbb{R}^n$, it came with a "standard coordinate basis", and linear transforms were the same as matrices. Later, I learned I was supposed to treat abstract vector spaces abstractly without specifying an arbitrarily-chosen basis or working in coordinates. Even later, I learned that sometimes there is a "canonical" basis and it's powerful to work in those coordinates after all. In this talk, we'll look at the cohomology and K-theory of some moduli spaces of flags and loops and see that they have canonical bases, with applications to the combinatorics of symmetric and quasisymmetric functions.

Thursday, October 13             Joshua Swanson (University of Southern California)

"Spinny pictures": connecting Catalan combinatorics, alternating sign matrices, and plabic graphs

Abstract: "Rotating" trees is a key step in balancing data structures like B-trees and AVL-trees. Modern databases and digital life are built upon this surprisingly crucial operation. Mathematically, a particularly beautiful instance of tree rotation arises by bijectively encoding complete binary trees as non-crossing matchings on a circle and literally spinning the circular matching. Certain non-obvious properties on the tree level become obvious when translated to the context of such a "spinny picture".

Far from being an isolated curiosity, we will show that such "spinny pictures" serve as a bridge between a remarkably diverse array of topics spanning enumerative combinatorics, representation theory, and algebraic geometry. We will in particular discuss our recent resolution of a nearly 30-year-old problem related to work of Kuperberg and Khovanov involving promotion on 4-row rectangular tableaux. The background assumed will be low, and pictures will be plentiful.

Joint work with Christian Gaetz, Oliver Pechenik, Stephan Pfannerer, and Jessica Striker.

Tuesday, November 1          Tri-College Colloquium
Doug Anderson                at NDSU   


Abstract:  TBD


Tuesday, November 15          Tri-College Colloquium
 Michael Marmorstein          at Concordia 



Abstract:  TBD


Tuesday, December 6             Hongyan Hou (MSUM)


Abstract: TBD

Student Focused. Land Grant. Research University.

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Department of Mathematics - North Dakota State University 
Phone: 701.231.8171
Campus Address: Minard 408
Physical/Delivery Address: Minard 408. 1210 Albrecht Boulevard, Fargo, ND 58102
Mailing Address: NDSU Dept #2750 / PO Box 6050 / Fargo, ND 58108 - 6050
Office Hours: Monday - Friday 8:00 - 5:00

Last Updated: Tuesday, September 20, 2022 3:11:37 PM
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