The following talks were given in past semesters.
Usual location and time: 1:30 pre-seminar, 2:30 seminar, both in MC 5417.
January 15: Mahrud Sayrafi Cancelled on account of snow
January 22: No seminar on account of CAAC
January 29: Nathan Pagliaroli, Counting triangulations from bootstrapping tensor integrals
Click here for abstract
Tensor integrals are the generating functions of triangulations of pseudo-manifolds. Such triangulations are constructed by gluing simplices along facets. These generating functions satisfy an infinite system of recursive equations called the Dyson-Schwinger equations, derived by reclusively gluing together triangulations. Such integrals also satisfy positivity constraints. By combining the Dyson-Schwinger equations and positivity constraints in a process called bootstrapping we are able to deduce known results for the generating functions of certain classes of triangulations as well as find new explicit formulae. This talk is based on joint work with Carlos I. Perez-Sanchez and Brayden Smith.
February 5: Jonathan Boretsky, Excluding a line from positroids
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For all positive integers $\ell$ and $r$, we determine the maximum number of elements of a simple rank-$r$ positroid without the rank-$2$ uniform matroid $U_{2,\ell+2}$ as a minor, and characterize the matroids with the maximum number of elements. This result continues a long line of research into upper bounds on the number of elements of matroids from various classes that forbid $U_{2,\ell+2}$ as a minor, including works of Kung, of Geelen–Nelson, and of Geelen–Nelson–Walsh. This is the first paper to study positroids in this context, and it suggests methods to study similar problems for other classes of matroids, such as gammoids or base-orderable matroids. This project is based on joint work with Zach Walsh.
February 12: Santiago Estupiñán, Jeu de Taquin for Mixed Insertion and a Problem of Soojin Cho
Click here for abstract
Serrano (2010) introduced the shifted plactic monoid, governing Haiman's (1989) mixed insertion algorithm, as a type B analogue of the classical plactic monoid that connects jeu de taquin of Young tableaux with the Robinson–Schensted–Knuth insertion algorithm. Serrano proposed a corresponding definition of skew shifted plactic Schur functions. Cho (2013) disproved Serrano's conjecture regarding this definition, by showing that the functions do not live in the desired ring and hence cannot provide an algebraic interpretation of tableau rectification or of the corresponding structure coefficients. Cho asked for a new definition with particular properties. We introduce such a definition and prove that it behaves as desired. We also introduce the first jeu de taquin theory that computes mixed insertion. This is joint work with Oliver Pechenik.
February 19: No seminar on account of reading week
February 26: Adrien Segovia, The dimension of semidistributive extremal lattices
Click here for abstract
The order dimension of a partially ordered set (poset), which is often difficult to compute, is a measure of its complexity. Dilworth proved that the dimension of a distributive lattice is the width of its subposet on its join-irreducible elements. We generalize this result by showing that the dimension of a semidistributive extremal lattice is the chromatic number of the complement of its Galois graph (see Section 3.5 of arXiv:2511.18540). We apply this result to prove that the dimension of the lattice of torsion classes of a gentle tree with $n$ vertices is equal to $n$. No advanced background is required to follow the talk. March 5: Maria Gillespie, A Positive Combinatorial Rule for $\psi$ Class Products on Multicolored Spaces
Click here for abstract
We use a new combinatorial construction and a sign-reversing involution to simplify an alternating sum that arises naturally in intersection theory on moduli spaces of curves. In particular, it is well known that a product of $\psi$ classes on the moduli space $\bar{M}_{0,n}$, the most commonly studied compactification of the moduli space $M_{0,n}$ of choices of $n$ distinct marked points on $\mathbb{P}^1$, is equal to a multinomial coefficient and has many natural combinatorial interpretations.
There are similar $\psi$ class products on other compactifications of $M_{0,n}$, including the "multicolored" spaces, in which the answer is a positive integer and yet only signed summation formulas were known. We simplify the alternating sum formula in the multicolored case to give a positive combinatorial rule, and discuss some applications of the formula. This is joint work with Vance Blankers and Jake Levinson.
March 12: Stephan Pfannerer (pre-seminar by Oliver Pechenik), Rotation-invariant web bases from hourglass plabic graphs
Click here for abstract
In 1995 Kuperberg introduced a collection of trivalent web bases encoding tensor invariants of $U_q(\mathfrak{sl}_3)$. Extending these bases to general $\mathfrak{sl}_r$ has remained an open problem. We present a solution for the case $r=4$ by introducing hourglass plabic graphs, a new generalization of Postnikov's plabic graphs. This is joint work with Christian Gaetz, Oliver Pechenik, Jessica Striker, and Joshua Swanson.
March 19: Moriah Elkin, Open quiver loci, CSM classes, and chained generic pipe dreams
Click here for abstract
In the space of type A quiver representations, putting rank conditions on the maps cuts out subvarieties called "open quiver loci." These subvarieties are closed under the group action that changes bases in the vector spaces, so their closures define classes in equivariant cohomology, called "quiver polynomials." Knutson, Miller, and Shimozono found a pipe dream formula to compute these polynomials in 2006. To study the geometry of the open quiver loci themselves, we might instead compute "equivariant Chern-Schwartz-MacPherson classes," which interpolate between cohomology classes and Euler characteristic. I will introduce objects called "chained generic pipe dreams" that allow us to compute these CSM classes combinatorially, and along the way give streamlined formulas for quiver polynomials.
March 26: Ian George, Enumerating Convex Sets in Posets
Click here for abstract
Causal Set Theory (CST) is a theory of quantum gravity where spacetime is taken to be a locally finite poset, called a causal set. A central problem in CST is to determine physically relevant properties from the purely combinatorial information of the causal set. In 2014 Glaser and Surya demonstrated that the distribution of interval sizes of a causal set sprinkled into a region of Minkowski space contains information about the dimension of the underlying spacetime. In 2026 Surya showed that this distribution can be used to define a “closeness” function on causal sets that distinguishes by dimension and global topology. In this talk we present work motivated by these results which investigates the more general notion of convex sets, instead of intervals, of a poset. First, we will introduce a generating polynomial for convex sets in a finite poset and explore some of its properties. We will then show that this polynomial is a complete invariant for the family of series-parallel posets. Lastly, we discuss early results on the utility of this polynomial in CST. The pre-seminar will introduce relevant background on CST.
April 2: Hadleigh Frost, Nested nestings, Moment-Cumulant relations and the Combinatorics of the Cosmos
Click here for abstract
Cosmological correlation functions probe the quantum origins of structure in the universe and are a prototype for many calculations in physics. I will share recent work on the complexes, fans and polytopes associated to these functions based on arXiv:2602.21194 and ongoing work. Two structures lie at the heart of this story: (1) incidence relations between chains and anti-chains, (2) a notion of "nested sets of nested sets". Both structures can be studied for an arbitrary lattice, but building sets of the boolean lattice are my main motivation. Tuesday, April 7 in MC 6029: Ashleigh Adams, Promotion, plane partitions, partial evaluations, and webs
Click here for abstract
Webs are graphical objects that give a tangible, combinatorial way to compute and classify tensor invariants. Recently, Gaetz, Pechenik, Pfannerer, Striker, and Swanson (arXiv:2306.12501) found a rotation-invariant web basis for $\mathrm{SL}_4$, as well as its quantum deformation $U_q(\mathfrak{sl}_4)$, and a bijection between move equivalence classes of $\mathrm{SL}_4$-webs and fluctuating tableaux such that web rotation corresponds to tableau promotion. They also found a bijection between the set of plane partitions in an $a\times b\times c$ box and a benzene move equivalence class of $\mathrm{SL}_4$-webs by determining the corresponding oscillating tableau. In this talk, I will similarly find the oscillating tableaux corresponding to plane partitions in certain symmetry classes by characterizing them via certain lattice words. A dynamical action on tableaux, called promotion, corresponds to rotation of $\mathrm{SL}_4$-webs. I will show how promotion of certain subtableau align with rotation of their respective webs. I will also show that this correspondence maps through a projection to either $\mathrm{SL}_2$ or $\mathrm{SL}_3$ webs. Moreover, that this projection is exactly a partial evaluation of webs. This talk will be given through the lens of the combinatorics of webs and tableau. Some of this work is joint with Jessica Striker. April 9: Mahrud Sayrafi, Constructing exceptional collections for toric varieties
Click here for abstract
Exceptional collections are a powerful tool for understanding the derived category of coherent sheaves on algebraic varieties, with applications in commutative algebra, birational geometry, and mirror symmetry. While the existence of exceptional collections is known for classical varieties such as Grassmannians and flag varieties, constructing explicit collections for toric varieties presents challenges in combinatorial algebraic geometry. In this talk I will describe a computational approach to constructing full strong exceptional collections consisting of complexes of line bundles for toric varieties.
No background in derived categories is assumed.
April 16: Tyler Dunaisky, Cosmological Correlators and Triangulating the Dual Cosmological Polytope
Click here for abstract
A cosmological correlator is an Euler integral, associated to a graph G, which encodes information about the state of the early universe. Evaluation of these integrals is extremely challenging, even in simple cases. However, it turns out the integrand can be identified with the so-called canonical form of the cosmological polytope, revealing a rich combinatorial structure and allowing the application of techniques from commutative algebra. I'll sketch my contribution to this story and advertise the fledgling field of positive geometry, which seeks to generalize the notion of canonical forms to geometric objects more exotic than polytopes.
April 23 (outside of term!): Melissa Sherman-Bennett, Dimer face polynomials in knot theory and cluster algebras
Click here for abstract
The set of dimers (aka perfect matchings) of a connected bipartite plane graph G is a distributive lattice, as shown by Propp. The order relation on this lattice comes from the "height" of a dimer, which is a vector of nonnegative integers. In this talk, I'll focus on the dimer face polynomial of G, which is the height generating function of all dimers of G. This polynomial has close connections to knot invariants on the one hand, and cluster algebras on the other. I'll discuss joint work with Mészáros, Musiker and Vidinas in which we explore these connections. No knowledge of knot theory or cluster algebras will be assumed.
September 11: Alex Wilson, Centralizers in the Plactic Monoid
Click here for abstract
Let $u$ be a word over the positive integers. Motivated in part by a question of representation theory, we study the centralizer set $C(u)$, which consists of words $w$ for which $wu$ and $uw$ are Knuth-equivalent. In particular, we characterize $C(u)$ when $u$ has few letters or is a certain type of decreasing sequence, and we address related enumerative questions.
September 18: There will be a watch party for a relevant talk from this ICERM workshop.
September 25: Jesse Huang, A Combinatorial Gateway to Calabi-Yau Toric Geometry
Click here for abstract
The goal of this talk is to introduce Calabi-Yau toric geometry from a purely combinatorial perspective, through the rich structures carried by an embedded bipartite graph on a torus called a dimer model.
In the pre-talk, we will demonstrate how matchings, tilings, and quivers naturally encodes deep geometric and physical content. No background in algebraic geometry will be assumed; instead, we’ll build the story from the ground up, with an emphasis on visual intuition and discrete structures.
Next, I will discuss how dimer models simultaneously encode the data of a toric Calabi-Yau singularity and its mirror dual, unifying perspectives from the B-model and A-model of homological mirror symmetry through noncommutative algebras. We will proceed with some recent developments and open problems, including connections to the symplectic geometry of Landau-Ginzburg models and Van den Bergh’s noncommutative resolution conjecture for toric Gorenstein affine singularities. To conclude the talk, we will discuss an example of a higher dimensional generalization and its connection to my recent research works.
This talk is also partially based on two undergraduate research projects in the present semester, where we study variations of dimer models of the same lattice polygon from different choices in the fast inverse algorithm, and implications on the two sides of mirror symmetry:
- (DRP) Dimer Variation and Geometry of Landau-Ginzburg Models, with Kenneth Xiao and Elizabeth Cai (A-model)
- (NSERC USRA) Dimer Variation and NCCR Mutations, with Filip Mildrag and Elana Kalashnikov (B-model)
October 2: Nathan Pagliaroli, Enumerating planar stuffed maps as hypertrees of mobiles
Click here for abstract
A planar stuffed map is an embedding of a graph into the 2-sphere, considered up to orientation-preserving homeomorphisms, such that the complement of the graph is a collection of disjoint topologically connected components that are each homeomorphic to the 2-sphere with multiple boundaries. This is a generalization of planar maps whose complement of the graph is a collection of disjoint topologically connected components that are each homeomorphic to a disc. In this talk I will outline my work in constructing a bijection between bipartite planar stuffed maps and collections of integer-labelled trees connected by hyperedges such that they form a hypertree. This bijection directly generalizes the Bouttier-Di Franceso-Guitter bijection between bipartite planar maps and mobiles. Additionally, we show that the generating functions of these trees of mobiles satisfy both an algebraic equation, generalizing the case of ordinary planar maps, and a new functional equation. As an example, we explicitly enumerate a class of stuffed quadrangulations.
October 9: Graham Denham, Distances in trees and inequalities for matroids
Click here for abstract
The distance matrix of a tree appears in a range of contexts, from phylogenetics to physical chemistry. I will describe a new result about the spectrum of this matrix, one that gives affirmative answers to two questions about matroid positivity properties. These are both strengthenings of Mason's conjectures about the log-concavity of sequence of numbers of independent sets of a matroid, proposed by Igor Pak and by Giansiracusa, Rincón, Schleis, Ulirsch, respectively.
This is joint work with Federico Ardila, Sergio Cristancho, Chris Eur, June Huh, and Botong Wang.
October 16: No seminar on account of reading week
October 23: Krystal Guo, Counting Substructures in Hypergraphs with Spectrum
Click here for abstract
Jacobi’s classical result expresses the generating function for closed walks at a vertex of a graph as the ratio of two characteristic polynomials. We find a hypergraph analogue of this relationship, showing that the same rational function for a hypergraph also counts combinatorial substructures within it, called infragraphs. We use Viennot’s Heaps of Pieces framework to establish this result for the adjacency tensor of a hypergraph. As an immediate consequence, we obtain an alternative proof for the monotonicity of the principal eigenvalue of a hypergraph. This is based on joint work with Joshua Cooper and Utku Okur (arXiv: 2411.03567).
October 30: Isabella Fosberry, Minimising the Martin invariant
Click here for abstract
The Martin invariant of an even degree regular graph is an integer, defined by a recurrence at a vertex. In this talk, we define this invariant and review some of its properties, and then focus on the following question: which graphs minimise the Martin invariant?
November 6: Leigh Foster, Tilings of Benzels (and other finite regions) in the hexagon grid
Click here for abstract
In 1990, Conway and Lagarias introduced tilability criteria for tilability for finite regions of the hexagon and square grids. In the same year, Thurston expanded upon their work, introducing the height function criterion. We will discuss some new results in tilability: A new tilability criteria via the $\textsf{SL}_2(\mathbb{C})$ double dimer model, and enumeration of tilings of special regions called Benzels, introduced in 2020 by Propp, using a technique called compression. If time allows, we will also discuss ongoing work that expands Thurston's height function to stone-and-bone tilings of the hexagon grid.
November 13: Pierre Popoli, Generalized Abelian Complexities for Pisot-Type Substitutive Sequences
Click here for abstract
Two finite words are said to be abelian equivalent if one is a permutation of the letters of the other. For an infinite word, one can investigate the associated complexity function, called abelian complexity, which is a classical object of study in combinatorics on words. In particular, many works study the abelian complexity of automatic sequences, where a longstanding conjecture states that the abelian complexity of an automatic sequence is a regular sequence. We have studied when the abelian complexity can be computed efficiently, in particular using the theorem prover Walnut. To this end, we study words that are fixed points of Pisot-type substitution and prove that these words satisfy the conjecture.
If time permits, I will present k-abelian complexities, which are intermediate complexities between the abelian complexity and the factor complexity. I will also explain how our results can be extended to these complexities and how we can obtain a two-dimensional linear representation of some examples.
This talk is based on joint work with J-M Couvreur, M. Delacourt, N. Ollinger, J. Shallit, and M. Stipulanti (arXiv: 2504.13584).
November 20: No seminar on account of Tim Miller’s defense
November 27: Zeus Dantas E Moura, Deterministic and Probabilistic Bijections for Macdonald Polynomials
Click here for abstract
Permuted-basement Macdonald polynomials \(E_α^σ(x_1, ..., x_n; q, t)\) are nonsymmetric generalizations of symmetric Macdonald polynomials indexed by a composition α and a permutation σ. They can be described combinatorially as generating functions over augmented fillings of shape α and basement σ.
We construct deterministic and probabilistic bijections on fillings that prove identities relating \(E_α^σ, E_α^{σ s_i}, E_{s_i α}^σ,\) and \(E_{s_i α}^{σ s_i}\). These identities arise from two operations on the shape and basement: swapping adjacent parts of the shape, which expands \(E_α^σ\) into \(E_{s_i α}^σ\) and \(E_{s_i α}^{σ s_i}\); and swapping adjacent basement entries, which gives \(E_α^σ = E_α^{σ s_i}\) when \(α_i = α_{i+1}\).
This is joint work with Olya Mandelshtam.
December 4: Taylor Brysiewicz, The degrees of Stiefel Manifolds
Click here for abstract
The set of orthonormal bases for $k$-planes in $\mathbb{R}^n$ is cut out by the equations
$X*X^T = I$
where $X$ is a $k \times n$ matrix of variables and $I$ is $k \times k$ identity. This space, known as the Stiefel manifold $\textrm{St}(k,n)$, generalizes the orthogonal group and can be realized as the homogeneous space $O(n)/O(n-k)$. Its algebraic closure gives a complex affine variety, and thus, it has a degree.
I will discuss our derivation of these degrees. Extending 2017 work on the degrees of special orthogonal groups, joint work with Fulvio Gesmundo gives a combinatorial formula in terms of non-intersecting lattice paths. This result relies on representation theory, commutative algebra, Ehrhart theory, polyhedral geometry, and enumerative combinatorics.
I will conclude with some open problems inspired by these objects.
May 8: Max Wiesmann, Arrangements and Likelihood
May 15: Félix Gélinas, Source characterization of the hypegraphic posets
May 22: No seminar on account of CanaDAM
Tuesday May 27: Note Tuesday date on account of AlCoVE
1:30pm: Elise Catania, A Toric Analogue for Greene’s Rational Function of a Poset
2:30pm: Jesse Kim, Shifted Parking functions
June 5: Alex Fink, The external activity complex of a pair of matroids
June 12: Laura Pierson, Power sum expansions for the Kromatic symmetric function
June 19: Elana Kalashnikov, The Abelian/non-Abelian correspondence and Littlewood-Richardson rules for two-step flags
June 26: Leo Jiang, Oriented graded Möbius algebras
July 3: Farhad Soltani, Quasisymmetric harmonics in superspace
July 10: Karen Yeats, Sizes of witnesses in covtree
July 17: Library archives visit
July 24: No seminar on account of FPSAC
July 31: URA day
1:30pm: Kai Choi, Alice in Quadraticspanningforestidentityspace
2:10pm: Peiran Tao, Algebraic Diagonals and Asymptotics of Bivariate Generating Functions
2:50pm: Stephanie Penner, Combinatorial Exploration: Counting Chord Diagrams
August 7 (12:00pm in MC 6029): Harper Niergarth, Reflected and Nonsymmetric Crystal Graphs
August 7 (1:30pm): Tia Ruza, Multivariate Limit Theorems and Algebraic Generating Functions
January 16: Leigh Foster, The squish map and the SL2 double dimer model
January 23: Karen Yeats, Combinatorial interpretation of the coefficients of the causal set theory d’Alembertian
January 30: Nantel Bergeron, Equivariant quasisymmetry
February 6: Hunter Spink, New perspectives on quasisymmetry via divided differences, flag varieties, etc.
February 14 (postponed on account of snow): Yasaman Yazdi, Statistical Fluctuations in the Causal Set-Continuum Correspondence
February 20: Reading week
February 27: Katie Waddle, Spherical friezes
March 6: Andrew Sack, Operahedron Lattices
March 13: Stephen Melczer, Positivity of P-Recursive Sequences Satisfying Linear Recurrences
March 20: Allen Knutson, Schubert calculus by counting puzzles
March 27: Michael Borinsky, Asymptotic count of edge-bicolored graphs
April 3: Harper Niergarth and Kartik Singh, The quasisymmetric Macdonald polynomials are quasi-Schur positive at $t = 0$
April 10: Natasha Ter-Saakov, Log-concavity of random Radon partitions
September 12: Jerónimo Valencia, A combinatorial proof of an identity involving Eulerian numbers
September 19: Karen Yeats, Tubings of rooted trees and resurgence
September 26: Jonathan Leake, Approximately Counting Flows via Generating Function Optimization
October 3: John Smith, Coefficient Positivity and Analytic Combinatorics
October 10: Josh Swanson, Cyclotomic generating functions
Tuesday October 15 (during reading week): Christian Gaetz, Hypercube decompositions and combinatorial invariance for Kazhdan-Lusztig polynomials
October 24: Nick Olson-Harris, Sufficient conditions for equality of skew Schur functions
October 31: Joseph Fluegemann, Smooth points on positroid varieties and planar $N=4$ supersymmetric Yang-Mills theory
November 7: Stephan Pfannerer, Descents for Border Strip Tableaux
November 14: Colleen Robichaux, Vanishing of Schubert coefficients
November 21: Torin Greenwood, Coloring the integers while avoiding monochromatic arithmetic progressions
November 28: Mike Cummings, Combinatorial rules for the geometry of Hessenberg varieties
December 5: David Wagner, Valuable partial orders
May 16: Sarah Brauner, Configuration spaces and combinatorial algebras
May 23: Li Yu, Integrable systems on the dual space of Lie algebras arising from log-canonical cluster structures
May 30: Jette Gutzeit, Introducing the interval poset associahedron
June 6: Tia Ruza, Central Limit Theorems via Analytic Combinatorics in Several Variables
June 13: Karen Yeats, Chord diagrams, triangulations, and $\phi \rho$ amplitudes
June 20: No seminar
June 27: Paul Balduf, Combinatorial proof of a Non-Renormalization Theorem
July 4: No seminar
July 11: No seminar
July 18: Laura Pierson, Two variations of the chromatic symmetric function Note: No preseminar this week
July 25: no seminar on account of FPSAC
August 1: URA day
1pm: Connor Baetz, The ASEP and alternate multi-line queues
1:30pm: coffee
1:50pm: Arnav Kumar, Dimension of posets and random graph orders
2:30pm: Ron Cherny, A Combinatorial Case of The Gerstenhaber Problem
August 8: William Chan, Control over the Kerov-Kirillov-Reshetikhin bijection with respect to the nesting structure on rigged configurations
August 15: Jang Soo Kim, Lecture hall graphs and the Askey scheme
January 25: Santiago Estupinan, A new shifted Littlewood-Richardson rule
February 1: Arad Nasiri, Combinatorial Action in Causal Set Quantum Gravity
February 8: Tim Miller, Vertex models for the product of a Schur and Demazure polynomial
February 15: Karen Yeats, More Martin and $c_2$ details
February 22: Reading week
February 29: Leo Jiang, Real matroid Schubert varieties, zonotopes, and virtual Weyl group
March 7: social time
March 14: Nancy Wallace, Quasi-partition algebras representations, planar Quasi-partition algebras and Characters of the Motzkin-Riordan algebra
March 21: Nathan Pagliaroli, Colored unstable map enumeration from random noncommutative geometries
March 28: Harper Niergarth, On the faces of the Kunz cone and the numerical semigroups within them
April 4: Olya Mandelshtam, A new formula for the symmetric Macdonald polynomials via the ASEP and TAZRP
April 11: Alex Kroitor, Lattice Paths Through ACSV
April 18: Jeremy Chizewer, Analytic Methods and Combinatorial Plants
September 14: Tianyi Yu, Analogue of Fomin-Stanley algebra on bumpless pipedreams
September 21: Jeremy Chizewer, The Sunflower Problem: Restricted Intersections
September 28: Kartik Singh, Closure of Deodhar components
October 5: Karen Yeats, Diagrammatic boundary calculus for Wilson loop diagrams
October 12: Reading week, no seminar
October 19: Vasu Tewari, Forest polynomials and harmonics for the ideal of quasisymmetric polynomials
October 26: David Wagner, Higher-order correlation inequalities for random spanning trees
November 2: Jerónimo Valencia, Snake decompositions of lattice path matroids
November 9: Spencer Daugherty, Extended Schur functions and bases related by involutions
November 16: Alejandro Morales, Linear relations and Lorentzian property of chromatic symmetric functions
November 23: Jason Bell, Filtered deformations of commutative algebras. Note, no pre-seminar this week
November 30: Kelvin Chan, Polarization operators in superspace
January 12: Andy Wilson (Kennesaw State University), Coinvariants and superspace
January 19: François Bergeron (LACIM), From the nabla operator to the super nabla operator
January 26: Emily Barnard (De Paul University), Cluster combinatorics and poset topology
February 2: Nick Olson-Harris (Waterloo), Binary tubings and Dyson-Schwinger equations
February 9: Elana Kalashnikov (Waterloo), Quantum hooks and the Plücker coordinate mirror
February 16: Stephen Gillen (Waterloo), Geometry of gradient flows for analytic combinatorics
February 23: Reading week (no seminar)
March 2: Social hour
March 9: Joel Lewis (George Washington University), Bargain hunting in a Coxeter group
March 16: Kartik Singh (Waterloo), Taking limits in Go-diagrams
March 23: Lucas Gagnon (York University), Quasisymmetric varieties, excedances, and bases for the Temperley–Lieb algebra
March 30: Freddy Cachazo (Perimeter), Arrangements of Pseudolines, Tropical Grassmannians, and Generalized Scattering Amplitudes