Combinatorics, Algebra and Geometry Seminar (CAGS)

February 9

Helly-Type Theorems on Support Lines for Families of Congruent Disks in the Plane

Tyler Russ, George Mason University

February 16

Hamiltonicity and related properties in K_r+1-free graphs

Aleyah Dawkins, George Mason University

March 15

Compatible transfer systems for C_p^r_q^s

Valentina Zapata Castro, University of Virginia

March 22

On locally finite ordered rooted trees and their rooted subtrees

Aleyah Dawkins, George Mason University

April 5

Research directions on Hopf algebras

Van Nguyen

April 19

Prettier Images

Mark Burge

September 22 

Recent Developments s in the Fundamental Theorem of Algebra

Mohsen Aliabadi, University of California San Diego

September 29 (virtual, on Zoom)

On the Partition Regularity of ax + by = cw^mzⁿ

Sohail Farhangi, The University of Adam Mickiewicz, Poznan, Poland

October 13

When is the group of units as additively closed as
possible?

Neil Epstein, George Mason University

October 20

How to show that a ring has uncountable krull
dimension

Jack J Garzella, University of California San Diego

October 27

Combinatorial Aspects of the Alternating Sign Matrix

Elizabeth A. Dinkelman, George Mason University

December 1 at 11:00am (virtual, on zoom)

Real-time Formalization of Mathematics

Kevin Buzzard, Imperial College, London, United Kingdom

Spring 2023

February 3 - In person and zoom

Egyptian integral domains

Neil Epstein, GMU

March 3 - In person and zoom

Helly-type theorems on support lines for convex bodies in the plane

Valeriu Soltan, GMU

March 24 - Zoom

Generalized Turán problems and a new localized approach

Rachel Kirsch, GMU

April 7 - Zoom

Coloring Reconfiguration

Reem Mahmoud, Virginia Commonwealth University,

April 14 - In person and zoom

A semigroup presentation for the singular part of the partial endomorphism monoid of a free G-act (of finite rank)

Scott Carson, GMU

April 28 - In person and zoom

Multiplier ideals and klt singularities via (derived) splittings

Peter Morton McDonald, University of Utah

May 3 - In person and zoom - 11am-12pm - Note! Unusual day and time

Perfectoid signature and an application to étale fundamental groups

Karl Schwede, University of Utah

October 28 - In-person and Zoom

Global perinormality in a generalization of a D +M construction and graded perinormality

Hannah Klawa, GMU

November 4 - In-person and Zoom

Infinitude Results for Prime Polynomials

Brian L. Johnson, Northern Virginia Community College

November 11 - In-person and Zoom  -  The talk is postponed until further notice.

Perfectoid signature and an application to étale fundamental groups - 

Karl Schwede, The University of Utah

November 16 - Zoom (NB! Unusual time: Wednesday 12:30 -- 1:30 PM EST)

Parity property of hexagonal sliding puzzles

Érika Roldán, The Max Planck Institute

November 18 - Zoom

Local Brooks’ Theorems

Magnús Már Halldórsson, Reykjavık University, Iceland

December 2 - In-person and Zoom - (NB! Unusual time: 2:30 -- 3:30 PM EST)

Distractions and Generic Initial Ideals

Anna-Rose Wolff, Mary Baldwin University

February 24 (virtual)

Canonical forms of neural ideals

Rebecca R.G., George Mason University

March 11 (in person)

Boundedly Polyhedral Sets and F-Simplices

Valeriu Soltan, George Mason University

March 25 (in person and virtual)

Promotion, rotation, and a web basis of invariant polynomials from noncrossing partitions

Jessica Striker, North Dakota State University

April 1 (in person and virtual)

Arithmetic Dynamics on Character varieties

Cigole Thomas, George Mason University

April 8 (in person and virtual)

What makes a diagram commute?

Richard H. Hammack

April 22 (virtual) - Postponed until Fall 2022

Parity Property of Hexagonal Sliding Puzzles

Érika Roldán, Technische Universitat Munchen

• October 8 (virtual)~ Groups, lattices, and closure operators
  Arturo Magidin
• October 15 (virtual)~ Permutation statistics and moment sequences
  Einar Steingrímsson
• October 29 (virtual)~ Higher dimensional origami constructions 
  Adriana Salerno
• November 5 (virtual)~ Universal Partial Cycles
  Rachel Kirsch
• November 12~ Hurwitz action in complex reflection groups
  Jiayuan Wang
• December 3 (virtual)~ Deep neural networks and DNA variant effect predictions in humans
  Ágúst Egilsson

• February 26~ Ideals of skew-symmetric matrix Schubert varieties 
  Brendan Pawlowski 
• March 12~ Whitney duals and Whitney twins: a plausible approach to questions related to Whitney numbers 
  Rafael S. González Di León
• March 19~ Sum-product and convexity 
  Brandon Hanson
• April 9~ Probabilistic generalizations of the Robinson– Schensted correspondence 
  Gabriel Frieden
• April 16~ Steiner configurations ideals: containment and colorability
  Abu Chackalamannil Thomas 
• April 23~ Data Science – Requirements and Applications 
  Colton Magnant

• September 18~ Dedekind, Prüfer, Krull, and factorial rings with or without zerodivisors 
  Jesse Elliot
• September 25~ The Free Cone and its relation to matroid invariants 
  Kevin Long
• October 2~ Independent sets, Lovasz’ theta, and linear programming 
  Craig E. Larson
• October 16~ From Efron's coins to alternation acyclic tournaments 
  Gabor Hetyei
• October 23~ Minimal free resolutions of fiber products
  Hugh R. Geller
• October 30~ Separating hyperplanes of convex sets
  Valeriu Soltan

• January 31~ ECH capacities, Ehrhart theory, and toric varieties
  Ben Wormleighton
• February 7~ Connected sums of Gorenstein Artin rings
  Ela Celikbas
• February 21~ Tiling, Terry Tao, Group Characters, and Fugledes Conjecture
  Sam Ferguson
• March 20~ TBA Postponed until further notice!
  Jack Love
• March 27~ TBA Postponed until further notice!
  Jesse Elliott
• April 24~ Independent sets, Lovasz’ theta, and linear programming Postponed until further notice!
  Craig E. Larson
• May 1~ TBA Postponed until further notice!
  Kevin Long

• September 13~ A few problems on matrix rings
  Geir Agnarsson
• September 20~ Magic type labelings of cycle products
  Dalibor Froncek
• September 27~ Generalized Rings
  Carl Weisman
• October 18~ Involutions and pseudo-involutions in the Riordan group
  Alexander Burstein
• November 1~ The ring of differential operators in a generalized Stanley-Reisner ring
  Janet Vassilev
• November 15~ M-decomposable convex sets
  Valeriu Soltan
• November 22~ Trace modules over commutative rings
  Haydee Lindo
• December 6~ The dynamics of Boolean networks
  Reinhard Laubenbacher

• February 1~ Vertex colorings of acyclic digraphs, efficiencies and discrepancies
  Geir Agnarsson
• March 1~ Lech’s inequality and the Stuckrad-Vogel conjecture
  Patricia Klein
• March 29~ Counting factorizations in complex reflection groups
  Joel Brewster Lewis
• April 5~ On the number of discrete chains
  Eyvindur Ari Pállson
• April 12~ Minimal generating sets for coordinate rings of representations
  Sean Lawton
• April 19~ Circular coloring of planar graphs
  Dan Cranston
• May 3~ No CAGS talk (MEGL poster session, hallway right outside EXPL 4106)
  GMU mathematics students.

• September 7~ A proof of the strict monotone 5-step conjecture
  Walter Morris
• September 14~ Pseudoalgebras
  Carl Weisman
• October 5~ Moreau-Type Characterizations of Polar Cones
  Valeriu Soltan
• October 19~ Positivity in the S1-equivariant cohomology of type A Peterson varieties
  Brent Gorbutt
• October 23~Tuesday\ 11 am -- 12 noon, ROOM 3301 EXPL. HALL. Polymatroids and excluded minors
  Carolyn Chun
• November 2~ Nearly Platonic graphs
  Dalibor Froncek
• November 9~ Helly-type results on support lines for disjoint families of unit disks
  Valeriu Soltan
• November 30~ The role of big Cohen-Macaulay modules and algebras in commutative algebra
  Rebecca R.G.

• February 2~ Interval posets, parity representations, binary partitions, and antiprisms (Part I: 12:30 -- 1:00 pm)
  Jim Lawrence
• February 9~ Interval posets, parity representations, binary partitions, and antiprisms (Part II)
  Jim Lawrence
• February 23~ Colored subgraphs whose forbiddance implies monochromatic connectivity
  Colton Magnant
• March 2~ When does the content map on polynomials act like a homomorphism, and how broadly does the answer apply? (Postponed until March 9)
  Neil Epstein
• March 30~ Hamiltonian cycles in critical graphs with large maximum degree
  Yue Zhao
• April 6~ Routing numbers of some graphs
  Gexin Yu
• April 13~ The Set-Maxima problem
  Indranil Banerjee
• April 27~ Diffuse Interfaces and Topology: A Phase-Field Model for Willmore’s Energy (Special Applied Math and CAGS Joint Seminar)
  Stephan Wojtowytsch
• May 4~ Applications of ordinary voltage graph theory and intersection theory to graph embeddability, (and some notes about topological data analysis) (NB! 11:30 am, due to Math Dept luncheon)
  Steven Schluchter

• September 8~ Sequential Importance Sampling Algorithms for Estimating Tree Size
  Alathea Jensen
• September 15~ Extremal finite subgraphs of the grid graph
  Geir Agnarsson.
• October 6~ Permutation Routing Via Matchings
  Indranil Banerjee.
• October 20~ SIAM Faculty Seminar
• October 27~ Separation and polarity properties of convex cones
  Valeriu Soltan.
• November 3~ Algebraic and combinatorial interpretations of tight closure theory on Stanley-Reisner rings
  Thomas Ales.
• November 10~ Unbalanced Wilf-equivalence
  Alexander Burstein.
• December 1~ TBA postponed!
  Jacob Farinholt
• December 8~ Symbolic powers and differential operators
  Eloísa Grifo

• February 10~ Generalized depth in the perfect closure
  George E. Whelan
• February 24~ Acyclic digraphs giving rise to complete intersections
  Walter Morris
• March 3~ How well-behaved is your ring map? The Ohm-Rush content function reconsidered
  Neil Epstein
• March 24~ Distance magic and group distance magic graphs
  Dalibor Froncek
• April 21~ Edge-coloring of graphs and multigraphs
  Dan Cranston
• April 28~ Conjugation of Transitive Permutation Pairs and Dessins d'Enfants
  Sean J. Rostami
• May 5~ Hessenberg varieties and the Shareshian-Wachs conjecture
  Patrick Brosnan

• September 9~ Doubly weighted rooted trees and computer security systems
  Geir Agnarsson
• October 7~ Self-polar polytopes
  Alathea Jensen
• October 14~ A great tool from the polynomial method toolkit: the Alon-Füredi Theorem
  John R. Schmitt
• October 27~ NB! Thursday at 12 noon Decompositions of complete bipartite graphs into generalized prisms
  Dalibor Froncek
• October 28~ A new perspective on the G-Invariant of a matroid
  Joseph E. Bonin
• November 4~ Khovanskii bases, Newton-Okounkov polytopes, and tropical geometry of projective varieties
  Chris Manon
• November 18~ Minimal ring extensions
  Jay Shapiro

• February 12~ Max-weight rooted-subtree problem and computer security
  Geir Agnarsson
• March 4~ A directed Steinitz theorem for oriented matroid programming
  Walter Morris
• March 18~ Characteristic properties of ellipses
  Valeriu Soltan
• March 25~ The Diophantine Frobenius Problem: Past, Present and Future
  Elie Alhajjar
• April 1~ Even the Patriots can win Atlantic 10!
  Dalibor Froncek
• April 5~NB! Tuesday at 12:30! On the Maximum Genus of Planar Graphs
  Lara Sherif
• April 8~ Matrix rings and representations
  Sam Mendelson
• April 22~ Geometry of Peterson Varieties in Lie Type A
  Brent Gorbutt
• April 29~NB! At 12 noon! In pursuit of canonical structures on cellularly embedded graphs
  Jason Suagee

• September 18~ Differential graded manifolds as a model for derived manifolds
  David Carchedi
• October 2~ On a special class of general permutahedra
  Geir Agnarsson
• October 16~ Negatively Self-Polar Polytopes
  Alathea Jensen
• October 30~ LP Alchemy for the Stability Number of a Graph
  Craig Larson
• November 6~ Prime congruences and Krull dimension for additively idempotent semirings
  Kalina Mincheva
• November 13~ On the Geometry of Quantum Weak Measurements
  Jacob Farinholt
• December 4~ Self-dual embeddings of K_{4m,4n} in orientable and nonorientable pseudosurfaces with the same Euler characteristic
  Steven Schluchter

• February 13~ Various generating functions, a unifying approach
  Geir Agnarsson
• February 20~ The Dedekind-Mertens Theorem for power series and more generally arbitrary algebras over R
  Jay Shapiro
• February 27~ The Zariski topology on sets of semistar operations
  Dario Spirito
• March 6~ Algebraic measures of singularity
  Javid Validashti
• March 20~ Graph Theory Tools for Tournament Scheduling
  Dalibor Froncek
• March 27~ Mihalisin - Klee Theorem for Fans
  Rachel Locke
• April 3~ Digital Geometry: New Trends and Developments
  Li Chen
• April 10~ The Complementarity Polytope, Pauli operators, and the Clifford Group
  Jacob Farinholt
• April 17~ Prime labelings of generalized Petersen graphs
  Kathryn Cokus, Ryan Ellingson, and Thomas Wilson (co Justin Z. Schroeder and Steven Schluchter)
• April 24~ The Survival Complex
  Anna-Rose Wolff
• May 1~NB! at 12 noon Homological algebra of graphs
  Arindam Banerjee

• August 29~ Parking functions & friends
  Matthias Beck
• September 5~ Applications of ordinary voltage graph theory to graph embeddability, part I
  Steve Schluchter
• September 19~ Base-Orderability in Matroids
  Thomas Savitsky
• October 17~ The Traveling Salesman Problem and P vs. NP: Some 1960s Theoretical Work at NIST On the Complexity of Mathematical Algorithms
  Jack Edmonds
• October 24~ Poincare-Bett Series of Monomial Rings
  Gwyneth Whieldon
• October 31~ Valuations on Convex Sets
  Jim Lawrence
• November 7~ Puzzles and (many flavors of) Schubert calculus
  Allen Knutson
• November 14~ Applications of ordinary voltage graph theory to graph embeddability, part II
  Steve Schluchter
• Decemver 5~ Some special matrix algebra presentations
  Samuel Mendelson

• January 31~ Induced subgraphs of hypercubes
  Geir Agnarsson
• February 21~ Mutually Unbiased Bases
  Jacob Farinholt
• February 28~ Ring extensions involving amalgamated duplications
  Tim Long
• March 28~ Triangle inequalities in representation theory and algebraic geometry
  Chris Manon
• April 4~ Ring extensions invariant under group action: flat epimorphic extensions
  Amy Schmidt
• April 11~ Test Ideals of Non-principal Ideals
  Karl Schwede
• April 18~ Threshold Digraphs
  James Shook
• May 2~at 12 noon! Strong Krull primes and flat modules
  Neil Epstein

• September 6~ Informal discussion on Gelfand-Tsetlin Polytopes (ongoing)
  Rebecca Goldin and Chris Manon
• September 13~ Informal discussion on Gelfand-Tsetlin Polytopes (ongoing)
  Rebecca Goldin and Chris Manon
• September 20~ Some naturally occurring matroids and matroid-like structures in commutative algebra
  Neil Epstein
• September 27~ A survey on graphs with a distinguishing partition
  Justin Z. Schroeder
• October 4~ Complete Intersection Affine Semigroup Rings Arising from Posets
  Walter Morris
• October 11~ Informal discussion on Gelfand-Tsetlin Polytopes (ongoing)
  Rebecca Goldin and Chris Manon
• October 18~ Informal discussion on Gelfand-Tsetlin Polytopes (ongoing)
  Rebecca Goldin and Chris Manon
• October 25~ Ordinary voltage graphs, pseudosurfaces, and derived graph embeddings with applications to graph embeddability
  Steven Schluchter
• November 8~ Hom polytopes between regular polytopes
  Jack Love
• November 22~at 11:30am The geometry of the quotient stack arising from a stacky fan
  David Johannsen

• February 1~ Schubert Calculus of Weighted Grassmannians
  Tomoo Matsumura
• February 8~ Zero-divisor graphs of nilpotent-free semigroups
  Neil Epstein
• February 15~ Coloring claw-free graphs with Δ-1 colors
  Dan Cranston
• March 1~ Zero-divisor graphs of nilpotent-free semigroups, part II
  Neil Epstein
• March 22~ "Graph" Saturation
  Michael Jacobson
• March 29~ Properties of the Copoint Graph of Convex Geometries
  Jonathan Beagley
• April 12~ Some basic properties of primary decomposition
  Yongwei Yao
• April 19~ Dimension and Height for Posets with Planar Cover Graphs
  Noah Streib
• April 26~ Approximating the Partition Function of the Ising Model
  Amanda Streib
• May 3~ Hyperbolic surfaces, circle maps and geometry of Teichmuller spaces
  Dragomir Saric

• September 7~ Clique Number and Chromatic Number of Graphs defined by Convex Geometries
  Walter Morris
• September 14~ Algebra and geometry of archimedean integers in general number fields
  Carl Weisman
• September 28~ Going-down in monoid rings
  Jay Shapiro
• October 5~ Turning conformal field theory into combinatorics
  Chris Manon
• October 12~ A Happy Coloring Theorem
  Jonathan Beagley
• October 19~ Pebbling in Split Graphs
  Glenn Hurlbert
• November 2~ Multi-Sources Simultaneous Communication in the Wireless Mobility Model is NP-complete
  Pattama Longani
• November 16~ Some problems in ring theory
  Geir Agnarsson

• February 3~ Schröder paths, partial horizontal strips, and symmetric functions
  Sangwook Kim
• March 2~ Davis matrics of sections and projections of polyhedral cones
  Jim Lawrence
• March 9~ On a Carathéodory theorem for Minkowski sum of polytopes
  Geir Agnarsson
• March 23~ Recent advances in biclique decompositions
  Walter Morris
• April 6~ On edge chromatic critical graphs
  Yue Zhao
• April 13~ Categorifications of the chromatic polynomial
  Radmila Sazdanovic
• April 20~ Carathéodory-type results for the sums and unions of convex sets
  Valeriu Soltan NB! Postponed until further notice.
• May 4~ Patterns in permutations
  Alexander Burstein

• September 9~ Induced subgraphs of Z2 and related extremal graphs
  Geir Agnarsson
• September 16~ An abstract structure theorem for suborder lower ideals of series-parallel posets
  Christian J. Altomare
• September 23~ Hamilton Bond, Tutte Bond and Tutte Theorem
  Xiaoyun Lu
• October 7~ Global Weyl modules for twisted loop algebras
  Prasad Senesi
• October 21~ Tropical geometry of flag varieties and the space of phylogenetic trees
  Chris Manon
• October 28~ Art Galleries, Fortresses, and Prison Yards: Illumination and Color
  T. S. Michael
• November 4~ An Introduction to Simplicial Geometries
  Cynthia S Merrick
• November 11~ The Order Dimension of Convex Geometries
  Jonathan Beagley
• November 18~ Applying the stuff we like: blocking semiovals and cryptology
  Keith Mellinger

• February 4~ The incidence algebra of a poset and enumerations
  Geir Agnarsson
• Febrary 18~ The type A Coxeter complex in algebraic combinatorics
  Forest Fisher
• Febrary 25~ A Projective approach to quantum error correcting codes
  Jacob Farinholt
• March 9, 12 noon -- 12:50 pm Unifying Laver's theorem and the Graph Minor Theorem via proof system minors
  Christian Altomare Note! This talk is on a WEDNESDAY at noon!
• March 11~ Convex quadrics
  Valeriu Soltan
• April 15~ A Projective approach to quantum error correcting codes, 2nd part
  Jacob Farinholt
• April 22~ Polytopes from graphs
  Jim Lawrence
• April 29~ Spies and revolutionaries
  Dan Cranston

• September 10~ Oriented Matroids and N-step Vectors
  Walter Morris
• September 17~ Combinatorial identities for subspaces and finite sets
  Geir Agnarsson
• October 8~ Combinatorial Hopf algebras by way of groups
  Forest Fisher, GWU
• October 22~ Some Interesting Classes of Convex Polytopes
  Jim Lawrence
• November 12~ An Attempt to Turn Geometry into Decorated Graphs
  Rebecca Goldin
• November 19~ Homology of distributive systems: a historical perspective
  Jozef Przytycki, GWU
• December 3~ Points, Copoints, and Colorings
  Jonathan Beagley
• December 10~ New Results on Graph-Theoretic Independence
  Craig Larson, VCU

• January 29~ The hitting time subgroup, Lukasiewicz paths, and Faber polynomials
  Gi-Sang Cheon, SungKyunKwan University S&T I room 242
• February 19~ Some graph labellings, complexities and connections to groups
  Geir Agnarsson S&T I room 206
• March 5~ Generalized rings: examples and applications
  Carl Weisman S&T I room 206
• March 19~ Workshop on Combinatorics, Enumeration, and Invariant Theory (WCEIT)
  S&T I room 242
• March 26~ Holes in a polytope defined by degree sequences
  Walter Morris S&T I room 206
• April 2~ On intersections and composites of minimal ring extensions
  Jay Shapiro S&T I room 206
• April 9~ Leavitt Path Algebras
  Gene Abrams, University of Colorado at Colorado Springs S&T I room 206
• April 23~ Ordered trees, the uplift principle and the Riordan group
  Lou Shapiro, Howard University S&T I room 206

• September 18~ Survey of recent papers on the Hirsch conjecture
  Walter Morris
• September 25~ Making K-theory combinatorial
  Rebecca Goldin
• October 2~ Betti numbers of graphs
  David Johannsen
• October 16~ f- and h-vectors for complexes, polytopes and beyond
  Geir Agnarsson
• October 23~ How Five Regular Solids Turned into Seventy-five
  Steve Morse
• October 30~ Helly-Type Results on Common Supports of Convex Bodies
  Valeriu Soltan
• December 4~ Topology of real coordinate arrangements
  Sangwook Kim

• January 30~ Mixed dominating matrices
  Walter Morris
• February 16 (Monday at 2:30 in S&T I, room 220)~ The Graham-Pollak Theorem and Alon-Saks-Seymour Conjecture
  Reza Naserasr, Carleton University
• February 27~ Embedding Quadratic Number Fields in Cyclotomic Fields
  Bill Ellis
• March 6~ Bruhat order and hyperplane arrangements
  Sangwook Kim
• March 20~ Thin Partially Ordered Sets
  Mikhail Matveev
• April 3~ The Geometry of Kissing: Soddy Circles, Apollonian Gaskets, and a Problem in Geometric Graph Theory
  Jill Dunham
• April 10~ On the flag polynomial of Minkowski sum of standard simplices
  Geir Agnarsson

• September 12~ Szekeres and Peters' computer proof of the 17-point Erdos-Szekeres problem
  Walter Morris
• September 19~ On the structure of the Minkowski sum of standard simplices
  Geir Agnarsson
• September 26~ On the structure of the Minkowski sum of standard simplices, Part II
  Geir Agnarsson
• October 3~ The lattice of cyclic flats of a matroid
  Joseph Bonin
• October 17~ On Minkowski rings
  Jim Lawrence
• October 24~ On the openness of the contraction map to the fixed ring
  Jay Shapiro
• October 31~ The free splice of matroids
  William Schmitt
• November 7~ Rational Representations of Flowers
  Jill Bigley Dunham
• November 14, 1:30 - 2:30 (NB! the time of the Applied and Computational Math Seminar)~ Random Threshold Graphs
  Edward Scheinerman
• November 21~ An Introduction to Lie Algebras and their Cohomology
  Robert F. Allen

• January 30~ (no talk)
• February 6~ (no talk)
• February 13~ The importance of fixed points in group actions on symplectic manifolds
  Rebecca Goldin
• February 20~ On rational distances between points on a quadratic curve in the Euclidean plane
  Steven D. Lepiere
• February 27~ Some Combinatorial Types of Polytopes
  Jim Lawrence
• March 5~ Universal lying-over rings
  Jay Shapiro
• March 26~ Graph labeling, complexity and variants
  Geir Agnarsson
• April 2~ Graph labeling, complexity and variants (2nd part, but self-contained!)
  Geir Agnarsson
• Friday April 4, 11:30 - 12:30, Room 242 (NB! time and place)~ Horse racing, card games, theorems in matrix theory, and consequences
  Chi-Kwong Li
• April 9~ Simple vertices in a Minkowski sums of simplices
  Walter Morris
• April 16~ (no talk)
• April 23~ (no talk)
• April 30~ The Cantor Tree and things that are like it
  Ronnie Levy

• Sept. 14~ Flag enumeration of matroid base poly\topes
  Sangwook Kim
• Sept. 21~ (no talk)
• Sept. 28~ Shellable complexes and topology of \diagonal arrangements
  Sangwook Kim
• Oct. 5~ Quadrilateral embedding of $G \times Q_s$\
  Paul C. Kainen
• Oct. 19~ Shellable complexes and topology of d\iagonal arrangements, part II
  Sangwook Kim
• Oct. 26~ Intordcutoin to Rnadom Garphs
  Nate Shank
• Nov. 9~ Graph theoretic proof of the Amitsur-Levits\ki theorem
  Geir Agnarsson
• Nov. 30~ We recommend the CDS/CCDS/Statistics Colloquium talk:
  Social Networks via Random Dot Product Graphs
  David Marchette

• Feb. 23~ Vertex coloring acyclic digraphs
  Geir Agnarsson
• Mar. 2~ Vertex coloring acyclic digraphs (Second Part)
  Geir Agnarsson
• Mar. 9~ (no talk)
• Mar. 16~ (Spring Break)
• Mar. 23~ An introduction to PPAD search problems
  Walter Morris
• Mar. 30~ (no talk, faculty meeting at 3:30)
• Aprli 6~ (no talk)
• April 13~ A quasisymmetric function for matroids
  Louis J. Billera
  NB! This is the first of two talks by Billera. The second talk will be later the same day at our departmental Colloquium.
• April 20~ Simple Arrangements of Pseudolines, and their Other Lives
  Jim Lawrence
• Aprli 27~ (no talk)
• May 4~ The Euler characteristic and Euler's formula for convex polytopes (with proofs)
  Jim Lawrence

• Sept. 15~ On Coin Graphs and Other Contact Graphs
  Geir Agnarsson
• Sept. 22~ Collineations and affine transformations in Euclidean space
  Valeriu Soltan
• Oct. 13~ Minkowski sums of simplices
  Walter Morris
• Oct. 20~ An algorithmic game related to Schubert calculus
  Rebecca Goldin
• Oct. 27~ Limits to Parallel Computation: P-Completeness Theory
  Ray Greenlaw, Armstrong Atlantic State University and Fulbright Scholar at Chiang Mai University
• Tuesday, Oct. 31, 12:15-1:05~ Physical Supersymmetry for Mathematicians
  Greg Landweber, University of Oregon
• Nov. 17~ Good Hidden P-matrix Sandwiches
  Walter Morris

• Feb. 10~ Sunflowers, Kneser Graphs and Intersecting Families
  Geoff McKenna, George Washington University
• Feb. 17~ No talk. We recommend the department
  colloquium at 3:30.
• Feb. 24~ On the empty hexagon theorem
  Walter Morris
• Mar. 3~ Gale transforms
  Jim Lawrence
• Mar. 10~ More Gale Transforms: K_5 in R^3 (or S^3)
  Jim Lawrence
• Mar. 24~ No seminar. The Math Club is arranging a talk at 1:15, on the Mathematics of Juggling, by Allen Knutson, UCSD.
• Mar. 31~ The transfer of Krull dimension in fixed rings
  Jay Shapiro
• April 7~ Invariants of n-tuples of points on the Riemann sphere under linear fractional transformations
  Ben Howard, UMCP
• April 14~ On finite groups
  Edith Adan-Bante, U. of Southern Mississippi Gulf Coast
• May 4~ 3PM The plus, minus game
  Klaus Fischer

• Sept. 8 ~ Graphical condensation and its connection to plane partitions and MacMahon's formula
  Eric Kuo
• Sept. 15 ~ A classification of the minimal ring extensions of an integral domain
  Jay Shapiro
• Sept. 22 ~ Combinatorics of Viterbi Sequences
  Eric Kuo
• Sept. 29 ~ The simple stochastic game
  Walter Morris
• Oct. 6 ~ Extension of vertex maps to graph homomorphisms
  Geir Agnarsson
• Oct. 13 ~ Extension of vertex maps to graph homomorphisms, part II
  Geir Agnarsson
• Oct. 20 ~ No talk
• Oct. 27 ~ Discrete polymatroids
  Walter Morris
• Nov. 3 ~ No talkNov. 10 ~ No talk
• Nov. 17 ~ Case Studies in Shape and Trajectory Optimization: Catenary Problem
  Igor Griva
• Dec. 1 ~ TBA
  Jim Lawrence

• Feb. 18 ~ Isothetic Parallelotopes and the Binary Intersection Property
  Valeriu Soltan
• Mar. 4 ~ Cluttered orderings for the complete bipartite graph and the complete tripartite graph
  Tomoko Adachi, Toho University, Japan
• Mar. 11 ~ Positive bases in Euclidean space
  Valeriu Soltan
• Mar. 25 ~ On multipartite posets
  Geir Agnarsson On multipartite posets
• Apr. 1 ~ Algebra and graph reconstruction
  Geoff McKenna, George Washington University Apr. 8 ~ NO TALK - we recommend the Math colloquium
• Apr. 22 ~ Good hidden P-matrix sandwiches
  Makoto Namiki, Toho University and George Mason University
• Apr. 29 ~ Good hidden P-matrix sandwiches, part II
  Makoto Namiki, Toho University and George Mason University