Combinatorics Seminar
Monday at 2:25pm
901 Van Vleck
Spring 2016 Schedule

     
January
25 William Cocke
On the number of elements in a group that are not kth powers
February
1 Shamgar Gurevich
Hierarchy in Representations of SL(2,q) 8 Paul Terwilliger
Tridiagonal pairs and L-operators for Uq(sl2) 15 Wen Liu (Hebei Normal U. China)
The incidence algebra of the classical polar space poset 22 Stefan Catoiu (DePaul U. Chicago)
Pythagorean counting in rank one restricted enveloping algebras 29 Steven Sam
Constructing algebras using invariant theory
March
7 Zhaochen Wang
Introduction to tridiagonal pairs 14 Sarah Bockting-Conrad (DePaul U. Chicago)
Some q-exponential formulas involving the double lowering operator psi for a tridiagonal pair 21 Spring Recess
28 Sarah Post (U. Hawaii at Manoa)
Quadratic algebras and orthogonal polynomials
April
4 Richard Brualdi
Combinatorial Matrices 11 Daniel Erman
Laurent polynomials and Eulerian numbers 18 Jae-ho Lee (Tohoku U. Japan)
A combinatorial interpretation of the nonsymmetric Askey-Wilson polynomials 25 Masato Tomiyama
The Terwillger algebra of a bipartite graph and its bipartite half
May
2 No meeting

Combinatorics Seminar
Monday at 2:25pm
901 Van Vleck
Fall 2015 Schedule

     
September
7 Labor day recess
14 (in B219VV) Darren Funk-Neubauer (Colorado State U. at Pueblo)
Bidiagonal pairs and bidiagonal triples 21 (in 120 Ingraham) Eric Ramos
Generalized representation stability and FI_d-modules 28 (in 120 Ingraham) Yang Yang
Upper triangular matrices and Billiard Arrays
October
5 (in 120 Ingraham) Steven Sam
Algebraic aspects of stability of Kronecker coefficients 12 (in 120 Ingraham) Richard Brualdi
Loopy, Hankel and combinatorially skew-Hankel tournaments 19 (in 120 Ingraham) Georgia Benkart
Walking on Representation Graphs 26 (in 901 VV) Hiroyuki Yamane (U. Toyama, Japan)
Centers of generalized quantum algebras
November
2 (in 901 VV) Wen Liu (Hebei Normal U. China)
The attenuated space poset Aq(N,M) 9 (in 901 VV) Alberto Elduque (U. Zaragoza, Spain)
Octonions 16 (in 901 VV) Yuta Watanabe (Tohoku U. Japan)
An algebra based on projective geometry with one fixed subspace 23 (in 901 VV) Zhaochen Wang
The Yang-Baxter equation 30 (in 901 VV) Rafael Cantuba (De La Salle U. Manila)
Lie algebra relations in the universal Askey-Wilson algebra
December
7 (in 901 VV) Yang Yang
Generalized adjoint actions 14 (in 901 VV) Paul Terwilliger
The equitable presentation for the quantum algebra Uq(sl2)

Combinatorics Seminar
Monday at 2:25pm
901 Van Vleck
Spring 2015 Schedule

     
January
26 Eric Ramos
Polynomial stability for representations of combinatorial categories
February
2 Aiping Deng (Donghua U. Shanghai)
Primary modules for the tetrahedron algebra 9 Paul Terwilliger
Topological aspects of the Z3-symetric Askey-Wilson relations 16 Richard Brualdi
All things Bruhat: matrix Bruhat decomposition, Bruhat order on permutation matrices, (0,1)- and integral matrices 23 Jae-ho Lee (Tohoku U. Japan)
Nonsymmetric Askey-Wilson polynomials and Q-polynomial distance-regular graphs
March
2 Takuya Ikuta (Kobe Gakuin U. Japan)
Complex Hadamard matrices and association schemes 9 Michael Schroeder (Marshall U. WV)
Completing latin squares: Haggkvist's conjecture and disjoint subsquares 16 Alison Gordon Lynch
A graph theoretic introduction to cluster algebras 23 Thao Vu (U. Tours, France)
Higher order relations for the q-Onsager algebra
April
6 Gabriel Pretel
Benedetti and Sagan's use of involutions in the study of antipodes for Hopf algebras 13 Zhaochen Wang
An action of PSL2(Z) on the universal Askey-Wilson algebra 20 Alison Gordon Lynch
Algebraic characterizations of Cauchy pairs and Uq(sl2)-modules (PhD defense) 27 (1:20 901VV) Gabriel Pretel
Tridiagonal pairs of Krawtchouk type and their compatible elements (PhD defense)
May
4 Mark MacLean (Seattle U.)
Algebraic and combinatorial relationships in bipartite distance-regular graphs

Combinatorics Seminar
Monday at 2:25pm
901 Van Vleck
Fall 2014 Schedule

     
September
8 Wei-Hsuan Yu (Michigan State)
New bounds for spherical two-distance sets and equiangular line sets 15 Frank Hall (Georgia State)
G-matrices, J-orthogonal matrices, and their sign patterns 22 Apoorva Khare (Stanford)
Faces and standard parabolic subsets of highest weight modules 29 (1:20 901VV) Adam Gal (Tel-Aviv U.)
Positive self-adjoint Hopf algebras 29 (2:25 901VV) Elena Gal (Tel-Aviv U.)
Symmetric self-adjoint Hopf categories and a categorical Heisenberg double
October
6 Richard Askey
Isoperimetric inequalities for rectangular prisms, or a second look at inequalities of Newton and Maclaurin 13 Aiping Deng (Donghua U. Shanghai)
Some even dimensional modules for the tetrahedron algebra 20 Richard Brualdi
Involutions by descents/ascents and symmetric integral matrices 27 Alison Gordon Lynch
Finite-dimensional irreducible modules for an even subalgebra of Uq(sl2)
November
3 Patricia Hersh (N. Carolina State)
Representation stabiltiy and Sn-module structure in the partition lattice 10 Georgia Benkart
A pedestrian approach to representation graphs 17 Paul Terwilliger
A classification of the lowering-raising triples 24 Gabriel Pretel
Humpert and Martin's antipode formula for the incidence Hopf algebra of graphs
December
1 Andrew Loveridge
Kac Moody Algebras I 8 James Hanson
Kac Moody Algebras II

Combinatorics Seminar
Monday at 2:25pm
901 Van Vleck
Spring 2014 Schedule

     
January
27 Jae-ho Lee
Bilinear forms, double affine Hecke algebras, and Q-polynomial distance-regular graphs
February
3 Ameera Chowdhury (Carnegie Mellon)
A Proof of the Manickam-Miklos-Singhi Conjecture for Vector Spaces 10 Max Glick (U. Minnesota)
Two singularity phenomena 17 Richard Brualdi
Tournaments from multigraphs 24 Eliseu Fritscher (UFRGS, Brazil)
The trace index of a (0,1)-matrix
March
3 Gabriel Pretel
Distance-regular graphs of q-Racah type and the universal Askey-Wilson algebra 10 Sarah Bockting-Conrad
Tridiagonal pairs and the quantum group Uq(sl2) 17 Spring Recess
24 Paul Terwilliger
Lowering-raising triples and the quantum group Uq(sl2) 31 Aiping Deng (Donghua U. Shanghai)
Characteristic polynomials of digraphs having a semifree action
April
7 Alison Gordon Lynch
Perfect state transfer on distance-regular graphs 14 Zhongshan (Jason) Li (Georgia State University)
Minimum ranks of sign pattern matrices via sign vectors and duality 21 Shamgar Gurevich
Weil representations and explicit Mordell--Weil lattices 28 Sarah Bockting-Conrad
Tridiagonal pairs, double lowering operators, and Uq(sl2)
May
5 Pascal Baseilhac (U. Tours, France)
The reflection equation, the q-Onsager algebra, and the algebra Aq.

Combinatorics Seminar
Monday at 2:25pm
901 Van Vleck
Fall 2013 Schedule

     
September
9 Paul Terwilliger
Billiard Arrays and the equitable presentation of Uq(sl2) 16 Alison Gordon Lynch
Large symmetric association schemes and the P-polynomial property 23 Robin Pemantle (U. Penn)
Double-dimer configurations and the hexahedron recurrence 30 Bogdan Ion (U. Pittsburgh)
BGG reciprocity for current algebras
October
7 Cathryn Holm
Special functions associated with root systems 14 Dragan Stevanovic (U. Primorska, U. Nis)
Spectral radius of some infinite graphs 21 Gabriel Pretel
Pascal matrices 28 Bill Martin (WPI)
Spherical designs, polynomial ideals, and association schemes
November
4 Hwa-Kyung Kim (Sangmyung U.)
Completions to an alternating sign matrix 11 Richard Brualdi
Permutations, X-rays, Tournaments, Partial Latin Squares, Transversals, and Skolem sequences 18 Matthias Lenz (Oxford U.)
On splines and counting lattice points in polytopes 25 Eliseu Fritscher (UFRGS, Brazil)
Finding eigenvalues of graphs with automorphism, part I
December
2 Eliseu Fritscher
Finding eigenvalues of graphs with automorphism, part II 9 Stefko Miklavic (U. Primorska)
Q-polynomial distance-regular graphs with girth 6

Combinatorics Seminar
Monday at 2:25pm
901 Van Vleck
Spring 2013 Schedule

     
January
28 Paul Terwilliger
The double lowering maps for a tridiagonal pair
February
4 Edward Hanson
Characterizations of Leonard pairs 11 Alison Gordon Lynch
The interplay of ranks of submatrices 18 Gabriel Pretel
The Temperley-Lieb algebra and sl2 25 Xiang Han (U.W. Whitewater)
Some methods related to the invariant theory of groups
March
4 No seminar
11 Cathryn Holm
A new approach to the bipartite fundamental bound 18 Hwa Kim
Generalized competition index of a primitive digraph 25 Spring recess
April
1 (1:20 901 VV) Peter Tingley (Loyola U.)
Affine Mirkovic-Vilonen polytopes 1 (2:25 901 VV) Emily Peters (Northwestern)
Planar algebras and evaluation algorithms 8 Jae-ho Lee
Nonsymmetric Askey-Wilson polynomials as vector-valued polynomials 15 Richard Brualdi
A Berlekamp permutation-switching problem 22 (1:20 901 VV) Jason Gaddis (U.W. Milwaukee)
Analogs of the harmonic oscillator problem 22 (2:25 901 VV) Lauren Williams (U.W. Milwaukee)
Invariant polynomial functions on tensors under the action of a product of orthogonal groups
May
6 Sarah Bockting-Conrad
Tridiagonal pairs of height one

Combinatorics Seminar
Monday at 2:25pm
901 Van Vleck
Fall 2012 Schedule

     
September
10 Gabriel Pretel
Compatible elements for a tridiagonal pair 17 Sarah Bockting-Conrad
Connections between quantum sl2 and tridiagonal systems 24 Jae-ho Lee
Q-polynomial distance-regular graphs and the DAHA of rank one
October
1 Paul Terwilliger
Finite dimensional irreducible Uq(sl2)-modules from the equitable point of view 8 Jang Soo Kim (U. Minnesota)
Moments of Askey-Wilson polynomials 15 Cathryn Holm
The girth of a thin distance-regular graph 22 Richard Brualdi
Alternating sign matrices and their patterns 29 Alison Gordon
Erdos-Ko-Rado theorems for Q-polynomial distance regular graphs
November
5 Vincent Genest (U. Montreal)
On the Clebsch-Gordan and Racah problems of sl_{-1}(2) and (-1)-orthogonal polynomials 12 Jonah Blasiak (U. Michigan)
Kronecker coefficients for one hook shape 19 Georgia Benkart
Combinatorics on the Weyl Side 26 Shamgar Gurevich
Bounds on characters of SL(2,q) via theta correspondence, with applications to the Ore conjecture
December
3 Zajj Daugherty (Dartmouth)
The quasi-partition algebra 10 Nathan Manning (U. Ottawa)
Global Weyl modules for equivariant map algebras

Combinatorics Seminar
Monday at 2:25pm
901 Van Vleck
Spring 2012 Schedule

     
January
23 Seth Meyer
Patterns of alternating sign matrices 30 Vidya Venkateswaran (CalTech)
Vanishing integrals for Hall-Littlewood polynomials
February
6 Ed Hanson
Fiedler's characterization of tridiagonal matrices 13 Sarah Bockting
Nomura's refinement of the split decomposition for a tridiagonal pair 20 Paul Terwilliger
The universal Askey-Wilson algebra 27 Tullia Dymarz
Rigidity and enveloping discrete groups by locally compact groups
March
5 Jonathan Lima
Symmetric function inequalities and Y-positivity 12 Thomas Roby (Visiting MIT)
Equivalence relations of permutations generated by constrained transpositions 19 Shuchi Chawla (UW CS dept)
Pricing via prophet inequalities 26 Gabriel Pretel
Finite-dimensional modules for the sl2 loop algebra
April
2 Spring Recess
9 Richard Brualdi
From classical majorization to poset majorization 16 Alison Gordon
An introduction to algebraic codes 23 Georgia Benkart
The McKay correspondence and walks on diagrams 30 Boyd Worawannotai
Dual polar graphs, the quantum sl2 algebra, and Leonard systems of dual q-Krawtchouk type
May
7 Jae-ho Lee
The Askey-Wilson algebra AW(3) and the double affine Hecke algebra of rank one 14 Stefko Miklavic (U. Primorska, Slovenia)
On distance-regular Cayley graphs for abelian groups

Combinatorics Seminar
Monday at 2:25pm
901 Van Vleck
Fall 2011 Schedule

     
September
12 Richard Brualdi
Matrix classes: old and new 19 Bostjan Frelih (U. Primorska, Slovenia)
Classification of cubic symmetric pentacirculants 26 Jernej Tonjek (U. Ljubljana, Slovenia)
A new inequality for distance-regular graphs
October
3 Melanie Matchett Wood
Counting points in configuration spaces 10 Amos Ron (UW CS dept)
Zonotopal algebra over finite graphs 17 Shamgar Gurevich
Fast matched filter and group representations: what, why, and how? 24 Gabriel Pretel
The A-like matrices for a hypercube 31 Boyd Worawannotai
Bipartite Q-polynomial distance-regular graphs and uniform posets
November
7 Eric Bach (UW CS dept)
An introduction to Widgetology 14 Philip Matchett Wood
Subset sums avoiding a single value 21 Seth Meyer
Isomorphisms of bipartite circulant graphs 28 Jae-ho Lee
Classification of the irreducible finite-dimensional representations for the double affine Hecke algebra of rank 1
December
5 Dima Arinkin (UNC-Chapel Hill)
Autoduality of Jacobians for singular curves 12 Alison Gordon
Cauchy pairs and Cauchy transition matrices

Combinatorics Seminar
Monday at 2:25pm
901 Van Vleck
Spring 2011 Schedule

     
January
24 Hajime Tanaka
A note on super Catalan numbers 31 Ana-Maria Castravet
Hypertrees and moduli spaces of stable rational curves
February
7 Dongho Moon
Permutation patterns and representation theory 14 George Brown
Leonard triples associated with hypercubes and their antipodal quotients 21 Seth Meyer
Bipartite circulant graphs and zero forcing 28 Gabriel Pretel
Baseilhac's hierarchy of mutually commuting elements in the tridiagonal algebra
March
7 Rie Tanaka
On a class of wreath products of hypergroups 14 Spring Recess
21 Georgia Benkart
Planar rook algebras and tensor representations of gl(1|1) 28 Michael Schroeder
Symmetric Hamilton cycle decompositions; some special cases
April
4 Alison Gordon
Cauchy pairs and transition matrices 11 "Turbo" Meng-Che Ho
Determinants of some tridiagonal matrices 15 (2:25 901 VV) Kailash Misra (North Carolina State U.)
Quantum groups and crystal bases 18 Jae-ho Lee
T-modules for Q-polynomial distance-regular graphs with a Delsarte clique 25 Sarah Bockting
Uq(sl2)-modules arising from tridiagonal systems
May
2 Shamgar Gurevich
Detecting the symmetry group of a molecule using cryo-electron microscopy

Combinatorics Seminar
Monday at 2:25pm
901 Van Vleck
Fall 2010 Schedule

     
August
30 Sarah Bockting
An operator associated with tridiagonal pairs
September
6 Labor day holiday
13 Paul Terwilliger
The classification of sharp tridiagonal pairs 20 Richard Brualdi
Matrices and Indeterminates 27 Sho Suda (Tohoku U. Japan)
Complex spherical designs and codes
October
4 Oleg Musin (U. Texas at Brownsville)
Positive definite functions in distance geometry 11 Boyd Worawannotai
Dual polar graphs and the quantum algebra Uq(sl2) 18 Michael Schroeder
phi-Hamilton cycle decompositions of the complete multipartite graph REDUX 25 Hajime Tanaka
Subsets with minimal width and dual width in Q-polynomial distance-regular graphs
November
1 Rie Tanaka
On the Terwilliger algebra of the Hamming graph with respect to a subset 8 Rachel Quinlan (U. Galway, Ireland)
Spaces of matrices without non-zero eigenvalues in their field of definition 15 Shifra Reif (Weizmann Institute)
Denominator identities for Lie superalgebras 22 Hiroshi Nozaki (Tohoku U. Japan)
Few distance sets and the Larman-Rogers-Seidel theorem 29 Hau-wen Huang
The classification of Leonard triples that have QRacah type
December
6 Edward Hanson
Leaves, tails, and Leonard pairs 13 Ali Godjali
Thin Hessenberg pairs and double Vandermonde matrices

Combinatorics Seminar
Monday at 2:25pm
901 Van Vleck
Spring 2010 Schedule

     
January
25 Paul Terwilliger
Double affine Hecke algebras of rank 1 and the Z3-symmetric Askey-Wilson relations
February
1 Rahbar Virk
An introduction to the combinatorics of category O 8 Hau-wen Huang (National Chiao Tung University, Taiwan)
The lit-only "sigma" game on a finite simple graph 15 Stefko Miklavic (U. Primorska, Slovenia)
On vertex-stabilizers of bipartite dual polar graphs 22 Richard Brualdi
(0,1)-Matrices and nonnegative eigenvalues
March
1 Seth Meyer
Computation of a generalization of the term rank of a semi-regular (0,1) matrix using a version of Hall's Theorem 8 Raimundas Vidunas (Kobe University, Japan)
Transformations between Heun and hypergeometric equations 15 Edward Hanson
Orthogonal polynomials and tridiagonal matrices 22 Gabriel Pretel
Four algebras related to tridiagonal pairs 29 Spring recess
April
5 Vladimir Tonchev (Michigan Tech)
Quantum codes from finite geometry and combinatorial designs 12 Rie Tanaka (Tohoku U. Japan)
On the association schemes with almost commutative Terwilliger algebras 19 Emeric Deutsch (Polytechnic Institute of New York U.)
Adjacent q-cycles in permutations 26 Michael Schroeder
phi-invariant Hamilton cycle decompositions
May
3 Gernot Michael Engel
Newton's inequalities on a lattice

Combinatorics Seminar
Monday at 2:25pm
901 Van Vleck
Fall 2009 Schedule

     
August
31 Edward Hanson
A characterization of Leonard pairs in terms of tails
September
7 Labor day
14 Aleksandar Jurisic (U. Ljubljana Slovenia)
The search for new distance-regular graphs 21 Xiaoguang Ma (MIT)
Quantum symmetric pairs and double affine Hecke algebras 28 Martha Yip
A Littlewood-Richardson rule for Macdonald polynomials
October
5 Don Kreher (Mich. Tech)
The degree sequence problem for partial Steiner triple systems 12 David Clark (Mich. Tech)
Designs, geometries, and Hamada's conjecture 19 Seth Meyer
Zero forcing sets 26 Ali Godjali
Thin Hessenberg pairs
November
2 Diana Cerzo
Thin irreducible T-modules for Q-polynomial distance-regular graphs 9 Hiroshi Suzuki (ICU Japan)
Tridiagonal spaces and Leonard pairs 16 Richard Brualdi
Completion of partial matrices to singular/nonsingular matrices 23 Michael Schroeder
Symmetric Hamilton cycle decompositions of graphs 30 Bridget Tenner (DePaul U.)
Homotopy type of the boolean complex of a Coxeter system
December
7 Sergei Sergeev (U. Birmingham UK)
Powers of matrices and periodicity questions in max algebra 14 Ales Drapal
Latin bitrades, equilateral triangles and abelian groups

Combinatorics Seminar
Monday at 2:25pm
901 Van Vleck
Spring 2009 Schedule

     
January
26 Paul Terwilliger
The Drinfel'd polynomial of a tridiagonal pair
February
2 Boyd Worawannotai
A Tutte polynomial for signed graphs 9 Diana Cerzo
Imprimitive Q-polynomial schemes 16 Ali Godjali
Properties of graded polynomial sequences and their duals 23 Adam Berliner
The Pesky Permanent Problem
March
2 Mihai Ciucu (U. Indiana)
Random tilings with gaps and electrostatics 9 Zajj Daugherty
Building my favorite centralizer algebras 16 Spring break
23 Richard Brualdi
Potentially nilpotent full sign patterns are spectrally arbitrary - a theorem of R. Pereira 30 Gabriel Pretel
q-geometric tridiagonal pairs and the quantum affine sl2 algebra
April
6 Louis Deaett
The sparse null space basis problem 13 Seth Meyer
Signed edge domination numbers in bipartite graphs 20 (1:20 901 VV) Hajime Tanake (Tohoku U. Sendai)
A bilinear form relating two Leonard systems 20 (2:25 901 VV) Rie Tanake (Tohoku U. Sendai)
Imprimitive Q-polynomial association schemes 27 Mike Schroeder
Latin squares composed of intercalates
May
4 Anna Saputera
Line graphs, root systems, and elliptic geometry 11 (2:00 pm, 901 VV) Boyd Worawannotai
Toward the cyclicly symmetric Askey-Wilson relations for dual polar graphs

Combinatorics Seminar
Monday at 2:25pm
901 Van Vleck
Fall 2008 Schedule

     
September
8 Paul Terwilliger
The classification of tridiagonal pairs of q-Racah type 15 Michael Gekhtman (Notre Dame)
Planar networks, Grassmannians and Poisson structures 22 George Brown
The Smith normal norm and acyclic matrices 29 Aleksandar Jurisic (U. Ljubljana Slovenia)
Distance-regular graphs with light tails
October
6 Michael Lang (Bradley U.)
Entrywise products of pseudo primitive idempotents 13 Plamen Iliev (Georgia Tech.)
Bispectrality of multivariable orthogonal polynomials 20 Bill Martin (WPI)
Lattices, mutually unbiased bases, hemisystems, and Q-polynomial association schemes. 27 Stefko Miklavic (U. Primorska, Slovenia)
The subconstituent algebra of a bipartite distance-regular graph
November
3 Richard Brualdi
Landau's and Rado's Theorems and partial tournaments 10 Louis Deaett
The minimum positive-semidefinite rank of a triangle-free graph 17 Andrei Calderaru
A spectral sequence from the ribbon graph bicomplex 24 Vadim Olshevsky (U. Connecticut)
Quasiseparable matrices and polynomials
December
1 Adam Berliner
TBA 8 Sergei Sergeev (U. Birmingham UK)
Two sided linear systems over max algebra

Combinatorics Seminar
Monday at 2:25pm
901 Van Vleck
Spring 2007 Schedule

     
January
22 Richard Brualdi
Matrix diagonals: something old and something new 24 (1:30, 901VV) Bridget Tenner
Reduced decompositions and permutation patterns 29 Dong-il Lee (Seoul Natl. U.)
Linear algebraic approach to Groebner-Shirshov basis theory
February
5 Amos Ron (U.W. Comp. Sci. Dept.)
Polynomial ideals and polynomial spaces over hyperplane arrangements and zonotopes 12 Stefko Miklavic (U. Ljubljana Slovenia)
Consistent cycles 19 Christoph Schwer
Galleries and q-analogs of symmetric functions 26 Paul Terwilliger
Evaluation modules for the three-point sl2 loop algebra
March
5 Jon Godshall
The q-tetrahedron algebra and the split decomposition of a Leonard Pair 12 (3:30 B131VV) Stefko Miklavic
Leonard triples and the hypercubes 19 Bill Martin (WPI)
Large bounds for binary codes from the subconstituent algebra 26 Kathleen Kiernan
Latin squares with forbidden entries
April
2 Spring break
9 Louis Deaett
Structural properties of triangle-free graphs 16 Lauren Williams (Harvard)
From total positivity on the Grassmanian to the asymmetric exclusion process 23 Mike Schroeder
The m-colored composition poset 30 Melvin Vidar
A family of tridiagonal pairs
May
7 Joohyung Kim
A duality between pairs of split decompositions for a Q-polynomial distance-regular graph 9 (2:25, B333 VV) Helene Barcelo (Arizona State U.)
The discrete fundamental group of the order complex of Bn

Combinatorics Seminar
Monday at 2:25pm
901 Van Vleck
Fall 2006 Schedule

     
September
11 Richard Brualdi
Matrix diagonals 18 Bill Martin (WPI)
An update on (t,m,s)-nets 18 (3:30pm, B341 VV) Alberto Grunbaum (Berkeley)
An ab-initio introduction to the bispectral problem 25 Bill Martin
Design systems: combinatorial characterizations of Delsarte T-designs
October
2 Arjana Zitnik (U. Ljubljana Slovenia)
Triangle-free distance-regular graphs with an eigenvalue multiplicity equal to the valency and diameter three 2 (3:30pm, B341 VV) Aleksandar Jurisic (U. Ljubljana Slovenia)
Characterization of the Patterson graph by its intersection array 9 Paul Hermann Zieschang (U. Brownsville TX)
Recent results and general questions in abstract scheme theory 16 James Parkinson
Iwahori cosets and alcove walks 23 Terry Gannon (U. Alberta CA)
What the trefoil knot can teach modular forms 30 Paul Terwilliger
Distance-regular graphs and the q-tetrahedron algebra
November
6 Claudia Malvenuto, University of Rome, La Sapienza
Pairwise colliding permutations and the capacity of infinite graphs 13 George Brown
Packing densities of layered permutations 20 Joohyung Kim
Characterization of some strongly regular graphs with parameters (64,28, 12, 12) 27 Ales Drapal
Latin trades and surfaces
December
4 (B305 VV) Ashwin Ganesan (U.W. ECE dept.)
Flows in information networks 11 Adam Berliner
Converting the permanent to the determinant

Combinatorics Seminar
Monday at 2:25pm
901 Van Vleck
Spring 2006 Schedule

     
January
23 Paul Terwilliger
The q-tetrahedron algebra 30 Richard Brualdi
Even posets and a parity result of Yaokun Wu
February
6 Susan Hollingsworth
The log-concavity of a famous sequence counting permutations 13 Jin-Yi Cai (UW Comp. Sci. Dept.)
Some results on matchcircuit computations and holographic algorithms 20 Christine Heitsch
Kreweras Complementation and Orbits in Catalan Lattices 27 Arun Ram
The Schur Hopf algebra
March
6 Lev Borisov
Introduction to the Leech lattice 13 Spring break
27 Martin Schlichenmaier (U. Luxembourg)
Higher genus affine Lie algebras of Krichever-Novikov type
April
3 Benjamin Otto
The Lie algebra G2 10 Jon Godshall
The universal central extension of the tetrahedron algebra 17 Han Hyuk Cho
Unicyclic graphs and competition numbers 24 Louis Deaett
Complexity and the structure of low-rank matrices
May
1 Patricia Hersh (U. Indiana)
The q=-1 phenomenon via homology concentration 5 Don Cartwright (U. Sydney, Rutgers) (2:25pm, B333 Van Vleck)
Groups acting simply transitively on the vertices of a building

Combinatorics Seminar
Monday at 2:25pm
901 Van Vleck
Fall 2005 Schedule

     
September
12 Paul Terwilliger
Distance-regular graphs and the quantum affine sl2 algebra 19 David Callan (UW Dept. of Statistics)
Generalizing the Catalan numbers 26 Nigel Boston
Risk and return considerations in The Weakest Link
October
3 Kathrin Bringmann
On mock theta functions and a conjecture of Dragonette and Andrews 10 Richard Brualdi
Latin squares, matroids, partitions, (0,1)-matrices, Young tableaux, graphs, matchings,... 17 Mikhail Klin (Ben Gurion U. Israel)
Links between Latin squares, nets, graphs and groups: work inspired by a paper of A. Barlotti and K. Strambach 24 Etsuko Bannai (Kyushu U. Japan)
On Euclidean designs 31 Sharon Garthwaite
Convolution congruences for the partition congruences
November
7 John Goldwasser (West Virginia U.)
Maximum size antichains and the COLEX order 14 Brian Hartwig
The tetrahedron algebra 21 Jackie Anderson
The largest (s,t)-core partition 28 Dina Christodoulopoul
An introduction to affine Weyl groups
December
5 H.K. Kim (Seoul Natl. U. Korea)
Competition indices of primitive digraphs 12 Louis Deaett
More on the Bruhat order for (0,1)-matrices

Combinatorics Seminar
Monday at 2:25pm
901 Van Vleck
Spring 2005 Schedule

     
January
24 Paul Terwilliger
Bidiagonal triples and the quantum algebra Uq(sl2) 31 Richard Brualdi
Some remarks on the Bruhat order for (0,1) matrices
February
7 Brian Hartwig
Onsager pairs and the Tetrahedron algebra 14 Richard Askey
q-factorial, q-gamma and q-beta functions 21 Nigel Boston
Capacity-achieving graph-based codes 28 Georgia Benkart
A combinatorial tripleheader: lambda-determinants, Schur functions, and perfect matchings
March
7 Christine Heitsch
Random de Bruijn sequences and the design of DNA codewords 14 Adam Berliner
Sidon sequences and magic graphs 21 Spring break
28 Han Cho
Competition graphs and numbers
April
4 Jim Propp
The combinatorics of Markoff numbers 11 Susan Hollingsworth
Cycle decompositions and path packings of K_nn 18 Bret Benesh
A survey of probabilistic group theory 25 Stephan Griffeth
TBA
May
2 Arlene Pascasio (U. De La Salle Philippines)
The pseudo primitive idempotents of a distance-regular graph

Combinatorics Seminar
Monday at 2:25pm
901 Van Vleck
Fall 2004 Schedule

     
September
13 Kyle Petersen (Brandeis)
Descent algebras and P-partitions 20 John Bowman
Symmetric functions and the cohomology of Springer fibers 27 Paul Terwilliger
The compact representation of a Leonard pair
October
4 Cathy Yan (Texas AM)
Noncrossing and nonnesting matchings 11 Richard Brualdi
Perfect Matching Preservers 18 Jaclyn Anderson
A proof of a conjecture of Stanton 25 Karl Mahlburg
A new approach to cranks and ranks
November
1 Jeremy Lovejoy (CNRS)
Extending partition theorems of Schur and Gollnitz to overpartitions 8 Pascal Vontobel
The edge zeta function of graphs and enumerating backtrackless, tailless cycles 15 Stefko Miklavic (Nova Gorica)
Some equitable partitions of Q-polynomial distance-regular graphs 22 Jose Dias da Silva (Lisbon)
Orthogonal dimension of orbital sets 29 Bob Wilson
Rook numbers and the normal ordering problem
December
6 Dina Christodoulopoul
Cluster algebras 13 Arun Ram
Paths, charge and Kostka-Foulkes polynomials

Combinatorics Seminar
Monday at 2:25pm
901 Van Vleck
Spring 2004 Schedule

     
January
26 Dick Askey
A determinant of Sylvester and some extensions
February
2 Stephen Griffeth
Schubert calculus, Hecke algebras, and the Yang-Baxter equation 9 Arun Ram
A new look at the path model 16 Paul Terwilliger
An extension of the quantum affine sl2 algebra 23 Open
March
1 Open
8 Adam Berliner, Rike Bostelmann, Louis Deaett
Sum choice numbers of graphs 15 Spring break
22 John Caughman (Portland State U.)
Distance-regular graphs and spin models 29 Holly Swisher
The Andrews-Stanley partition function and p(n)
April
5 Jose Dias da Silva
TBA 12 Marcelo Aguiar (Texas AM)
Loday's types of algebras and Rota's types of operators 19 Brian Hartwig
Three mutually adjacent Leonard pairs 26 Christine Heitsch
Further combinatorial results motivated by computational biology
May
3 Darren Neubauer
Raising and lowering maps and modules for the quantum affine sl2 algebra 10 John Hall
Semigroups and combinatorics: radicals, Schur functions, and sandwich matrices

Combinatorics Seminar
Monday at 2:25pm
901 Van Vleck
Fall 2003 Schedule

     
September
8 Jim Propp
Markoff numbers 15 Yuval Roichman (Bar Ilan)
Descent representations and the flag major index 22 Sergey Fomin (U. Michigan)
Double Bruhat cells: total positivity and cluster algebras 29 Slavik Jablan (Belgrade)
The Knot-theory program LinKnot
October
6 Jaclyn Anderson
On the existence of rook equivalent t-cores 13 Mona Musa (U. Illinois)
The double circulant conjecture for quadratic residue codes 20 No meeting
27 Lev Borisov
Complexity of binomial ideals
November
3 Richard Brualdi
Bigraphs, digraphs, SNS-matrices, tilings, and Aztec diamonds 10 Peter Orlik
Ranking patterns 17 Ada Chan (Caltech)
Jones pairs and association schemes 24 Patricia Hersh (U. Michigan)
A GL_n(q) analog of the partition lattice
December
1 Matt Ondrus
Whittaker modules, central characters and tensor products of modules for U_q(sl_2) 8 Susan Hollingsworth
k-ordered bipartite graphs

Combinatorics Seminar
Monday at 2:25pm
901 Van Vleck
Spring 2003 Schedule

     
January
27 Christine Heitsch
Combinatorial results motivated by computational biology
February
3 Arun Ram
Diagram algebras 10 Jeremy Lovejoy
Overpartitions 17 Lev Borisov
Jacobi triple product formula and boson-fermion correspondence 24 Paul Terwilliger
Some tridiagonal pairs associated with quantum affine sl2.
March
3 Sylvie Corteel
Lecture hall theorems 10 Uri Keich (UCSD)
On designing seeds for similarity search in genomic DNA 24 Eric Mortenson
Supercongruences for truncated hypergeometric series 31 Richard Brualdi
List colorings of graphs and SDRs
April
7 Jackie Anderson
Does there exist a [72,36,16] type II code? 14 Brian Hartwig
Leonard pairs in the representation theory of Uq(sl2) 21 Darren Neubauer
Introduction to the q-shuffle algebra 28 Steve Kirkland (U. Regina Canada)
Digraph-based conditioning for Markov chains
May
5 Richard Askey
A new look at Fibonacci numbers

Combinatorics Seminar
Monday at 2:25pm
901 Van Vleck
Fall 2002 Schedule

     
September
9 Nigel Boston
The probability of generating a finite group 16 Aleksandar Jurisic (U. Ljubljana Slovenia)
Locally GQ tight distance-regular graphs 23 Arlene Pascasio (U. De La Salle Philippines)
On the multiplicities of the primitive idempotents of a distance-regular graph 30 Paul Terwilliger
Leonard pairs and orthogonal polynomials
October
7 Hjalmar Rosengren (Chalmers U. Tech. Sweden)
Leonard pairs and quantum group theory 14 Bogdan Petrenko (U. Illinois)
On the sum and the product of two primitive elements of maximal subfields of a finite field 21 Stephen Griffeth
Alternating sign matrices and the K-theory of flag varieties 28 Mourad Ismail (U. South Florida)
Rogers-Ramanujan identities and difference equations
November
4 Richard Brualdi
Matrices in combinatorics with applications 11 Jacob Christiansen (U. Copenhagen Denmark)
The log-normal moment problem 18 Brian Hartwig
Clusters of Leonard pairs 25 Georgia Benkart
Aztec diamonds and the (in)famous rho
December
2 Yang Chen (Imperial College UK)
Generalized Chebyshev Polynomials 9Timo Seppalainen
Increasing path models and interacting particle systems

Combinatorics Seminar
Monday at 2:25pm
901 Van Vleck
Spring 2002 Schedule

     
January
28 Yiftach Barnea
Hausdorff dimensions and the Nottingham group
February
4 Paul Terwilliger
Two linear transformations each tridiagonal with respect to an eigenbasis for the other: a canonical form 11 Morgen Bills (U. Michigan)
Brauer tableaux, Brauer polytabloids, and some sign-reversing involutions 18 Arun Ram
Generalizing the dominance order on partitions 25 Antal Balog
What is A if A+A is small?
March
4 Karl Mahlburg
Partition identities and a theorem of Zagier 11 Hiroshi Suzuki (Ohio State U.)
Type II matrices and their Bose-Mesner algebras 18 Richard Brualdi
Maximal nests of subspaces with an application to graph coloring 25 Spring break
April
1 Susan Hollingsworth
On a conjecture about trees in graphs with large girth 8 Patricia Hersh (U. Michigan)
Optimizing discrete Morse functions 12 Jonathan David Farley (U. Vanderbilt)
Differential posets and distributive lattices: a 1975 conjecture of Richard Stanley 15 Hans Schneider
The recent discovery of Wielandt's proof of the exponent inequality for primitive nonnegative matrices 22 Geir Helleloid
The m-step competition graph of a digraph 29 Kendra Nelsen
Charge and the Kostka-Foulkes polynomial
May
6 Georgia Benkart
Some Temperley-Lieb combinatorics

Combinatorics Seminar
Monday at 2:25pm
901 Van Vleck
Fall 2001 Schedule

     
September
10 Arun Ram
Introduction to affine Hecke algebras 17 Jack Koolen (Eindhoven)
The energy of a graph 24 Richard Brualdi
Linear preservers and diagonal hypergraphs
October
1 Bill Martin (Worcester Polytechnic)
The biweight enumerator and the subconstituent algebra of the hypercube 8 Gerald Cliff (U. Alberta)
Determining irreducible modular GL(n,K)-modules 15 Ken Ono
Questions and theorems about t-core partitions 22 Hans Schneider
Diagonal scaling: sunny side up and once over lightly 29 Brian Curtin (U. South Florida)
Graph Homomorphisms and Graph Automorphisms
November
5 Eric Bach (CS dept UW)
Combinatorial analysis of quantum random walks 12 Hiroshi Suzuki (Ohio State U.)
On weakly distance-regular digraphs 19 Matt Bloss
Irreducible representations of a centralizer algebra of a complex reflection group 26 Alexander Kleshchev
Representations of alternating groups and beyond
December
3 Jack Koolen
Are there finitely many distance-regular graphs with fixed valency? 10 Brian Hartwig
Truncated hypergeometric series

Combinatorics Seminar
Monday at 2:25pm
901 Van Vleck
Spring 2001 Schedule

     
January
22 Paul Terwilliger
How to recognize a Leonard pair 29 Mike Lang
Distance-regular graphs and the Q-polynomial property
February
5 Jim Propp
Domino Tilings: enumeration, random generation, and asymptotics 12 Warren Johnson
Combinatorics of higher derivatives of inverse functions 19 Alberto Elduque
Maximal subalgebras of associative superalgebras 26 Bryan Shader (U. Wyoming)
Dynamics, digraphs and diophantine equations
March
5 Matt Bloss
Centralizer algebras of complex reflection groups 12 Spring break
19 Susan Hollingsworth
TBA 26 Alexei Borodin (U. Penn)
Harmonic analysis on the infinite symmetric group
April
2 Arnold Neumaier (U. Vienna, Austria)
Large-scale mixed model estimation for animal breeding and census data 9 Richard Askey
Some elementary combinatorics related to teaching 16 Alexei Zhedanov (Donetsk Inst. of Physics, Ukraine)
Spectral transformations, numerical algorithms, self-similarity and special functions 23 Paul-Hermann Zieschang (U. Kiel)
Local and global scheme theory 30 Gwynneth Coogan
A combinatorial identity and an application to Hurwitz Zeta functions
May
7 Free

Combinatorics Seminar
Monday at 2:25pm
901 Van Vleck
Fall 2000 Schedule

     
September
11 Alexsandar Jurisic (Nova Gorica Polytechnic, Slovenia)
Distance-regular graphs with the 1-homogenous property 18 Paul Terwilliger
Leonard pairs from 24 points of view 25 Susan Hollingsworth
Partitions of a graph into paths with prescribed endvertices and lengths
October
2 Arun Ram
Standard Young tableaux for classical type root systems 9 Jeremy Lovejoy
Arithmetic properties of combinatorial functions 16 Chris Godsil (U. Waterloo, CA)
Spin Models 23 Bill Martin (Worcester Polytechnic)
Width and Dual Width of Subsets in P- and Q- polynomial schemes 30 Katsuhisa Mimachi (Kyushu U. Japan)
Monodromy representations associated with a Selberg type integral; realization of the Iwahori-Hecke algebra
November
6 Robert Donnelly (Murray State U.)
Solitary bases for representations of semisimple Lie algebras 13 Norman Wildberger
A-D-E graphs and the mutation and numbers games 20 Georgia Benkart
Tensor powers of sl(r) 27 Andrei Kelarev
On transitive Cayley graphs of groups and semigroups
December
4 Mark Maclean
Latin squares without proper subrectangles 11 John Caughman (Portland State U.)
Bipartite distance-regular graphs with the Q-polynomial property