CombinaTexas 2020/21
Welcome to Virtual CombinaTexas 2021!
CombinaTexas, a combinatorics conference in the SouthCentral United States, is an annual regional conference on Combinatorics, Graph Theory, and Computing. It is dedicated to the enhancement of both the educational and research atmospheres of the community of combinatorialists and graph theorists in Texas and the surrounding states. The aim of the CombinaTexas series is to increase communication between mathematicians in the region, promote the research of the regional combinatorics community, and provide a forum for presentation and discussion of developments in the field of combinatorics.
For more information about the CombinaTexas series, click here.
Basic Information
Texas A&M University,
College Station, TX,
February 2021, 2021.
The conference will be done through ZOOM.
Registration
Registration is closed on Feb 13.
Information on the ZOOM link of the conference will be sent to regsitered participants on Feb 18.
Check the email account that you provided in the registration form.
Contact the organizer cyan@math.tamu.edu if the link is broken.
Plenary Speakers

Miklos Bona , University of Florida .

Title: + Permutation patterns and nonrational generating functions
The solution of an enumeration problem is very often a generating function $F$. Some problems are too difficult for us to find the explicit form of $F$. This is almost always so in the theory of pattern avoiding permutations In this talk, we will introduce a method that leads to negative results that are rare in this part of combinatorics. When our method applies, it shows that $F$ is not a rational function, which provides at least some explanation of the fact that the original enumeration problem is difficult. As an example, we will prove that for the overwhelming majority of permutation patterns, the generating function of the corresponding generating function is not rational.
 Tri Lai ,
University of NebraskaLincoln.

ChunHung Liu ,
Texas A&M University.

Title: + Clustered coloring for Hadwigertype conjectures
Hadwiger (Hajos, and Gerards and Seymour, respectively) conjectured that
the vertices of every graph with no K_{t+1} minor (topological minor,
and odd minor, respectively) can be colored with t colors such that any
pair of adjacent vertices receive different colors. These conjectures
are stronger than the Four Color Theorem and are either open or false in
general. A weakening of these conjectures is to consider clustered
coloring which only requires every monochromatic component to have
bounded size instead of size 1. It is known that t colors are still
necessary for the clustered coloring version of those three conjectures.
Joint with David Wood, we prove a series of tight results about
clustered coloring on graphs with no subgraph isomorphic to a fixed
complete bipartite graph. These results have a number of applications.
In particular, they imply that the clustered coloring version of Hajos’
conjecture is true for bounded treewidth graphs in a stronger sense.
They also lead to the first linear upper bound for the clustered
coloring version of Hajos’ conjecture and the currently best upper bound
for the clustered coloring version of the GerardsSeymour conjecture.
 Nathan Reading ,
North Carolina State University
Title: + Lattice congruences of the weak order: Algebra, combinatorics, and geometry
The talk will begin with a crash course on congruences on a finite
lattice and the corresponding lattice quotients. To make the case
that combinatorialists should care about congruences and quotients,
we’ll flip through some examples of lattice quotients of the weak
order. I will sketch a complete combinatorial model for congruences on
(and quotients of) the weak order on permutations and talk about how
it generalizes to other Coxeter groups. The talk will conclude with a
discussion of the connections to geometry, representation theory, and
string theory and a mention of current and future work.
 Stephanie van Willigenburg ,
University of British Columbia
Title: + The epositivity of chromatic symmetric functions
The chromatic polynomial was generalized to the chromatic symmetric
function by Stanley in his seminal 1995 paper. This function is
currently experiencing a flourishing renaissance, in particular the
study of the positivity of chromatic symmetric functions when expanded
into the basis of elementary symmetric functions, that is, epositivity.
In this talk we approach the question of epositivity from various
angles. Most pertinently we resolve the 1995 statement of Stanley that
no known graph exists that is not contractible to the claw, and whose
chromatic symmetric function is not epositive.
This is joint work with Soojin Cho, Samantha Dahlberg, Angele Foley and
Adrian She, and no prior knowledge is assumed.
 Josephine Yu ,
Georgia Institute of Technology
Title: + Topics in Real Tropical Geometry
I will introduce tropical geometry and discuss some recent developments and
future directions at the intersection of tropical geometry and real algebraic
or convex geometry.
Schedule and Abstracts (Central Standard Time)
Schedule
and Abstracts of Plenary Talks
Schedule and Abstracts of Contributed Talks
List of Registered Participants (by Feb 13, 2021)
Information of the ZOOM links will be distributed to registered participants
on Feb 18.
Saturday, February 20, 2021
(Central Standard Time)
08:20am08:30am 

Opening Remarks

08:30am09:30am 

Plenary Talk 1: Miklos Bona



Permutation patterns and nonrational generating functions

09:30am10:50am 

Contributed Session I


Session A 



09:30am09:50am 
Speaker: Hua Wang


Title: Combinatorics of colored compositions and spotted tilings

09:50am10:10am 
Speaker: Patrick Liscio


Title: The move poset in chipfiring

10:10am10:30am 
Speaker: Lauren Snider


Title: On 2dimensional parking functions

10:30am10:50am 
Speaker: Ayomikun Aderinan


Title: Invariant parking sequences



Session B 



09:30am09:50am 
Speaker: James Schmidt


Title: A cyclic variant of the ErdosSzekeres theorem

09:50am10:10am 
Speaker: Lutz Warnke


Title: Prague dimension of random graphs

10:10am10:30am 
Speaker: Nicolau Saldanha


Title: Domino tilings in dimension 3 and higher

10:30am10:50am 
Speaker: Soukaina Zayat


Title: About the Erd\"{o}sHajnal conjecture for sevenvertex tournaments.


10:50am11:10am 

Break

11:10 12:10pm 

Plenary Talk 2: ChunHung Liu



Clustered coloring for Hadwigertype conjectures

12:10pm  02:00pm 

Lunch Break

02:00pm03:00pm 

Plenary Talk 3: Nathan Reading



Lattice congruences of the weak order: Algebra, combinatorics, and geometry

03:00pm04:20pm 

Contributed Session II


Session A 



03:00pm  03:20pm 
Speaker: Byeongsu Yu


Title: Monomial ideals in an affine semigroup
rings

03:20pm  03:40pm 
Speaker: Diego Villamizar Rubiano


Title: On the generalized central factorial numbers

03:40pm  04:00pm 
Speaker: Christopher Wu


Title: A bound on tableau stabilization using lattice paths

04:00pm  04:20pm 
Speaker: Joshua Swanson


Title: DUSTPAN distributions as limit laws for Mahonian statistics on forests



Session B 



03:00pm03:20pm 
Speaker: Criel Merino


Title: Polyimatroids and algebraic invariants in graphs

03:20pm03:40pm 
Speaker: Chi Hoi Yip


Title: On maximal cliques of Cayley graphs over fields

03:40pm04:00pm 
Speaker: Semin Yoo


Title: A combinatorial correspondence between finite Euclidean geometries


and symmetric subsets of $\mathbf{\mathbb{Z}/n\mathbb{Z}}$

04:00pm04:20pm 
Speaker: Noureen Khan


Title: Topological conformation of DNA bound by virtual coloring


04:20pm04:40pm 

Break

04:40pm05:40pm 

Plenary Talk 4: Stephanie van Willigenburg



The epositivity of chromatic symmetric functions

06:00pm07:00pm 

Social time @ Gather Town

Sunday, February 21, 2021
(Central Standard Time)
08:20am  09:40am 

Contributed Session III


Session A 



08:20am  08:40am 
Speaker: Alex Chandler


Title: On the strength of chromatic symmetric homology for graphs

08:40am  09:00am 
Speaker: Jaewoo Jung


Title: Bounds on regularity of quadratic monomial ideals

09:00am  09:20am 
Speaker: Erica Ordog


Title: Sylvan structures on nearcones

09:20am  09:40am 
Speaker: Yiyang She


Title: Some multiplicity one theorems for wreath products



Session B 



08:20am  08:40am 
Speaker: Sakander Hayat


Title: CoEdgeregular graphs which are cospectral with the sextension 

of the square grid graphs

08:40am  09:00am 
Speaker: Suchakree Chueluecha


Title: The sunflower problem

09:00am  09:20am 
Speaker: Ana Laura Trujillo Negrete


Title: Laplacian spectrum of token graphs

09:20am  09:40am 
Speaker: He Guo


Title: On the power of random greedy algorithms


9:40am  10:00am 

Break

10:00am  11:10 

Plenary Talk 5. Josephine Yu



Topics in Real Tropical Geometry

11:00am  12:00pm 

Plenary Talk 6. Tri Lai



Tiling generating functions as classical group characters

  
12:00pm 01:50pm 

Lunch Break and Social time @ Gather Town




02:20pm  03:2pm 

Contributed Session IV


Session A 



02:00pm  02:20pm 
Speaker: Aram Bingham


Title: DIII clan combinatorics for the orthogonal Grassmannia

02:20pm  02:40pm 
Speaker: Matthew Samuel


Title: A positive formula for Schubert polynomial structure constants with   certain descent restrictions

02:40pm  03:00pm 
Speaker: Corey Wolfe


Title: The Borel submonoid of a symplectic monoid

03:00pm  03:20pm 
Speaker: George Nasr


Title: A combinatorial formula for KazhdanLusztig polynomials of sparse   paving matroids



Session B 



02:00pm  02:20pm 
Speaker: Carlos Alfaro


Title: Enumeration of cospectral and coinvariant graphs

02:20pm  02:40pm 
Speaker: Josephine E Reynes


Title: The integer matrix allminors matrixtree theorem via oriented hypergraphs

02:40apm  03:00pm 
Speaker: Evangelos Nastas


Title: An elementary DehnSydler theorem proof

03:00pm  03:20pm 
Speaker: Casey Schlortt


Title: Minimum conditions for bootstrap percolation on the cubic graph


Resources
A map of Texas A&M, and driving directions from the College Station airport.
A list of former CombinaTexas conferences.
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Acknowledgement:
This conference is supported in part by the
Institute for Mathematics and its Applications (IMA) through its Participating Institution (PI) Program. PI members may use IMA/PI funds to support personnel's travel to this conference."
This conference is also supported in part by
National Science Foundation, the Combinatorics Foundation,
and Department of Mathematics at Texas A&M University.
Organizers
Laura Matusevich (Texas A&M University)
Jacob White (University of Texas Rio Grande Valley)
Catherine Yan (Texas A&M University)