Seminars and colloquia

E.g., Jan. 29, 2022

Farid Aliniaeifard

Modular relations between chromatic symmetric functions 

February 1, 2022

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In 1995, Stanley introduced the chromatic symmetric functions. The study of chromatic symmetric functions of graphs inspired two main research directions. The first research direction is to prove the Stanley-Stembridge conjecture: if a poset is $(3+1)$-free, then the chromatic ... Read more
  • Discrete mathematics

Hemanshu Kaul

Illinois Institute of Technology
Chromatic polynomial and counting DP-colorings of graphs : Problems and progress

February 8, 2022

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In 1912, Birkhoff, introduced the chromatic polynomial of a graph G that counts the number of proper colorings of G. List coloring, introduced in the 1970s by Erdos among others, is a natural generalization of ordinary coloring where each vertex has a restricted list of colors ... Read more
  • Discrete mathematics

Colin Defant

Princeton University
Variants of pop-stack sorting

February 15, 2022

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The purpose of this talk is to advertise noninvertible combinatorial dynamics, a largely unexplored area with several interesting directions. We will focus on the pop-stack sorting map, a specific noninvertible operator on the symmetric group, along with several of its ... Read more
  • Discrete mathematics

Manik Dhar

The Kakeya Set conjecture over Z mod N for general N

February 22, 2022

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A Kakeya Set in (Z/N Z)^n is a set that contains a line in every direction. It has been known for over a decade that such sets must be large when N is prime (or more generally over any finite field). This goes back to Dvir's proof of the finite field Kakeya conjecture as posed ... Read more
  • Discrete mathematics

Brandon Hanson

University of Maine

March 1, 2022

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  • Discrete mathematics

Sergi Elizalde

Dartmouth College
Rowmotion on 321-avoiding permutations

March 8, 2022

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We give a natural definition of rowmotion for 321-avoiding permutations, by translating, through bijections involving Dyck paths and the Lalanne-Kreweras involution, the analogous notion for antichains of the positive root poset of type A. We prove that some permutation ... Read more
  • Discrete mathematics

Michael Simkin

Harvard University
The number of n-queens configurations

March 22, 2022

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The n-queens problem is to determine Q(n), the number of ways to place n mutually non-threatening queens on an n x n board. We show that there exists a constant 1.94 < a < 1.9449 such that Q(n) = ((1 + o(1))ne^(-a))^n. The constant a is characterized as the solution to a ... Read more
  • Discrete mathematics

Sergey Goryainov

Hebei Normal University and Chelyabinsk State University
On two types of cliques related to eigenspaces of strongly regular graphs

April 5, 2022

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We consider graphs without loops and multiple edges. A $k$-regular graph with $n$ vertices is called a strongly regular graph with parameters $(n,k,a,c)$ if any two adjacent vertices have exactly $a$ common neighbours and any two distinct non-adjacent vertices have $c$ common ... Read more
  • Discrete mathematics