Codes and Expansions (CodEx) Seminar

An international remote seminar on the theory and applications of harmonic analysis, combinatorics, and algebra.

Tuesdays at 10 a.m. PST / 1 p.m. EST / 6 p.m. UTC / 7 p.m. CET

Zoom. To access the Zoom link, please join the mailing list by entering your information here.

Recorded talks are on our YouTube channel.

Organized by:
Joey Iverson (Iowa State University)
John Jasper (Air Force Institute of Technology)
Emily J. King (Colorado State University)
Dustin Mixon (The Ohio State University)

Upcoming talks:

January 23, 2024 Edinah Koffi Gnang (Johns Hopkins University): "From graph decomposition to matrix apportionment and back" Abstract
January 30, 2024[SPECIAL TIME: 9 a.m. PST / Noon EST / 5 p.m. UTC / 6 p.m. CET] Oscar Mickelin (Princeton University)
February 6, 2024 Francesca Bartolucci (TU Delft)
February 13, 2024 Joseph Thomas Iosue (University of Maryland)
February 20, 2024 Abiy Tasissa (Tufts University)
February 27, 2024 Samuel Ballas (Florida State University)
March 5, 2024 Joe Kileel (University of Texas at Austin): "Covering Number of Real Algebraic Varieties and Beyond" Abstract
March 12, 2024 [SPRING BREAK: No talk.]
March 19, 2024 Demetrio Labate (University of Houston)
March 26, 2024 Elizabeth Munch (Michigan State University)
April 2, 2024
April 9, 2024 Jonathan D.H. Smith (Iowa State University)
April 16, 2024 Mátyás Domokos (Alfréd Rényi Institute of Mathematics)
April 23, 2024 Nathaniel Johnston (Mount Allison University)
April 30, 2024
May 7, 2024 Ole Christensen (Technical University of Denmark)

Past talks:

December 5, 2023 Hannah Lawrence (MIT): "Learning Polynomial Problems with SL(2,R)-Equivariance" Abstract | Video
November 14, 2023 Michael Catanzaro (Geometric Data Analytics, Inc.): "Topological Parallax: A Geometric Specification for Deep Perception Models" Abstract | Video
November 7, 2023 Daniel Freeman (St Louis University): "Recovering vectors from saturated measurements" Abstract | Video
October 31, 2023 Sylvester Eriksson-Bique (University of Jyväskylä): "BiLipschitz Embeddings of Manifolds, Orbifolds and Metric Spaces" Abstract | Video
October 24, 2023 Ben Blum-Smith (Johns Hopkins University): "Estimating a signal corrupted by a cyclic group action plus noise" Abstract | Video
October 17, 2023 Shira Faigenbaum-Golovin (Duke University): "Can We Approximate It? Manifolds, Refinable Functions, and the Approximation Power of Neural Networks" Abstract | Video
October 10, 2023 Dan Edidin (University of Missouri): "The second moment and the sparse multi-reference alignment problem" Abstract | Video
October 3, 2023 Courtney Paquette (McGill University): "Hitting the High-D(imensional) Notes: An ODE for SGD learning dynamics in high-dimensions" Abstract | Video
September 26, 2023 Mark Iwen (Michigan State): "Sparse Spectral Methods for Solving High-Dimensional and Multiscale Elliptic PDEs" Abstract | Video
September 19, 2023 Robert Webber (Caltech): "Rocket-propelled Cholesky: Addressing the challenges of large-scale kernel computations" Abstract | Video
September 12, 2023 Steven Gortler (Harvard University): "Invariant Embeddings" Abstract | Video
August 22, 2023[Summer Student and Postdoc Talks]
Efstratios Tsoukanis (University of Maryland): "Coorbit Invariant Embeddings" Abstract | Video
August 15, 2023[Summer Student and Postdoc Talks]
Daniel Packer (The Ohio State University): "Max Filtering with Reflection Groups" Abstract | Video
August 8, 2023[Summer Student and Postdoc Talks]
Arun Suresh (University of Missouri): "On the Generic Crystallographic Phase Retrieval Problem" Abstract | Video
August 1, 2023[Summer Student and Postdoc Talks]
Christopher Dock (Tufts University): "Instability of Quantum Tomography with Bounded Operators" Abstract | Slides | Video
July 25, 2023[Summer Student and Postdoc Talks]
David Bartusel (RWTH Aachen): "The role of connectedness in STFT phase retrieval" Abstract | Video
July 18, 2023[Summer Student and Postdoc Talks]
Keenan Eikenberry (Arizona State University): "Markov Kernels Valued in Wasserstein Spaces" Abstract | Video
July 11, 2023[Summer Student and Postdoc Talks]
Mitchell Taylor (UC Berkeley): "Stable phase retrieval in function spaces" Abstract | Video
June 27, 2023[Summer Student and Postdoc Talks]
Pu-Ting Yu (Georgia Tech): "Convergence of Frame Series" Abstract | Video
June 22, 2023[Summer Student and Postdoc Talks]
Donggeun Ryou (University of Rochester): "Near-Optimal Restriction Estimates for Cantor Sets on the Parabola" Abstract | Video
June 14, 2023[Summer Student and Postdoc Talks]
Dylan Domel-White (Vanderbilt University): "Algorithms and Guarantees for One-bit Phase Retrieval" Abstract | Video
June 6, 2023[Summer Student and Postdoc Talks]
Marc Christian Zimmermann (University of Cologne): "Critical lattices in the Gaussian core model" Abstract | Video
May 30, 2023[Summer Student and Postdoc Talks]
Josue Tonelli-Cueto (University of Texas San Antonio / Johns Hopkins University): "Condition Numbers and Probability for Explaining Algorithms" Abstract | Video
May 2, 2023Jakob Lemvig (Technical University of Denmark - DTU): "The Gabor frame set problem for Hermite functions" Abstract | Video
April 25, 2023James Murphy (Tufts University): "Intrinsically Low-Dimensional Models for Wasserstein Space: Geometry, Statistics, and Learning" Abstract | Video
April 18, 2023Margaret Cheney (Colorado State University): "Tuning to Target Resonances" Abstract | Video
April 11, 2023Shahaf Nitzan (Georgia Tech): "A set with no Riesz basis of exponentials" Abstract
April 4, 2023Bill Martin (Worcester Polytechnic Institute): "Quantum isomorphic graphs from association schemes" Abstract | Video
March 28, 2023Dustin G. Mixon (The Ohio State University): "Bilipschitz invariants" Abstract | Video
March 21, 2023Rachel Greenfeld (Institute for Advanced Study, Princeton): "The structure of translational tilings" Abstract
March 7, 2023Krystal Guo (University of Amsterdam and QuSoft): "Strongly regular graphs with a regular point" Abstract | Video
February 28, 2023Judith Packer (University of Colorado Boulder): "Wavelets coming from representations of graph C*-algebras" Abstract | Slides | Video
February 21, 2023Nadav Dym (Technion): "Efficient Invariant Embeddings for 3D point sets" Abstract | Video
February 14, 2023Alhussein Fawzi (Google DeepMind): "Discovering faster matrix multiplication algorithms with deep reinforcement learning" Abstract | Video
February 7, 2023Ursula Molter (Universidad de Buenos Aires): "Best 'good' subspace data fitting" Abstract | Video
January 31, 2023Ingemar Bengtsson (Stockholm University): "Pythagorean SICs" Abstract | Video
January 24, 2023Oleg Musin (University of Texas Rio Grande Valley) "Majorization and optimal spherical configurations" Abstract | Video
January 17, 2023Stefan Steinerberger (University of Washington): "Graphical Designs" Abstract | Slides | Video
December 6, 2022Bernhard Bodmann (University of Houston): "Spotting irregularities with reaction and diffusion: A scattering transform on graphs and extremes in log-normal random walks" Abstract | Video
November 29, 2022Tom Needham (Florida State University): "Symplectic Geometry and Fusion Frames" Abstract | Video
November 15, 2022Felix Voigtländer (Catholic University Eichstätt-Ingolstadt): "Sampling numbers of the Fourier-type Barron spaces" Abstract | Video
November 8, 2022Andreas Heinecke (Yale-NUS College): "Unsupervised statistical learning in ancient economic history" Abstract | Video
November 1, 2022Carlos Cabrelli (University of Buenos Aires): "Frames by Orbits of Operators and Model Spaces" Abstract | Video
October 25, 2022Kiyoto Yoshino (Tohoku University): "The Lemmens-Seidel conjecture for base size 5" Abstract | Video
October 18, 2022Doug Cochran (Arizona State University): "Geometry of Invariants for Generalized Coherence Tests" Abstract | Video
October 11, 2022Danylo Yakymenko (Institute of Mathematics of NAS of Ukraine): "On the continuous Zauner conjecture" Abstract | Video | Slides
October 4, 2022Dardo Goyeneche (Universidad de Antofagasta): "Mutually unbiased frames" Abstract | Video | Slides
September 27, 2022Pete Casazza (University of Missouri): "Piecewise Scalable Frames" Abstract | Video
September 20, 2022Travis Russell (Dartmouth College): "Quantum correlations via Operator Systems" Abstract | Video
September 6, 2022Michael Perlmutter (University of California Los Angeles): "Group Invariant Scattering on Graphs, Manifolds, and Other Measure Spaces" Abstract | Video | Slides
August 30, 2022John Jasper (Air Force Institute of Technology): "Equi-isoclinism from symmetry" Abstract | Slides | Video
August 23, 2022Jameson Cahill (University of North Carolina at Wilmington): "Max filtering" Abstract | Video
August 16, 2022[Summer Student and Postdoc Talks]
Matthias Wellershoff (University of Maryland): "Uniqueness of phase retrieval from sampled Gabor measurements: a short overview" Abstract | Video
August 9, 2022[Summer Student and Postdoc Talks]
Vicky Kouni (University of Athens): "Analysis Compressed Sensing: from Model-Based Methods to Deep Unfolding Networks" Abstract | Video
July 19, 2022[Summer Student and Postdoc Talks]
Victor Bailey (Georgia Tech) "Frames via Unilateral Iterations of Bounded Operators" Abstract | Video
July 12, 2022[Special Session on Recent Advances in Packing]
Shujie Kang (University of Texas at Arlington): "Non-informationally complete Gabor POVMs" Abstract | Video
July 5, 2022[Special Session on Recent Advances in Packing]
Shuxing Li (Simon Fraser University): "Packings of Partial Difference Sets" Abstract | Video
June 28, 2022[Summer Student and Postdoc Talks]
Simon Ruetz (Universität Innsbruck): "Adapted variable density subsampling for compressed sensing" Abstract | Video
June 21, 2022[Special Session on Recent Advances in Packing]
Xinyu (Norah) Tan (Duke University): "Quadratic Form Diagonal Gates and Grassmannian Packings" Abstract | Video
Zilin Jiang (Arizona State University): "Forbidden subgraphs and spherical two-distance sets" Abstract | Video
June 14, 2022[Special Session on Recent Advances in Packing]
Dustin G. Mixon (The Ohio State University): "An Approximate Positivstellensatz" Abstract | Video
Kasso Okoudjou (Tufts University): "Minimizing the p-frame potentials" Abstract | Video
June 7, 2022[Special Session on Recent Advances in Packing]
Gary Greaves (Nanyang Technological University): "Hermitian matrices of roots of unity and their characteristic polynomials" Abstract | Video
Matt Fickus (Air Force Institute of Technology): "Harmonic Grassmannian codes" Abstract | Video
May 31, 2022[Special Session on Recent Advances in Packing]
Emily J. King (Colorado State University): "The Combinatorics of Equiangular Tight Frame Substructures" Abstract | Video
Alexander Barg (University of Maryland): "Bounds for the sum of distances of spherical sets of small size" Abstract | Video
May 24, 2022[Special Session on Recent Advances in Packing]
Gene Kopp (Purdue University/Louisiana State University): "A step toward a constructive proof of Zauner's conjecture" Abstract | Video
May 3, 2022Amit Singer (Princeton University): "Method of moments in cryo-electron microscopy" Abstract | Video
April 26, 2022Doug Hardin and Nate Tenpas (Vanderbilt University): "Linear programming bounds for discrete periodic energy problems" Abstract | Video
April 19, 2022Deanna Needell (University of California Los Angeles): "Online nonnegative matrix factorization and applications" Abstract | Video
April 12, 2022Hau-Tieng Wu (Duke University): "Some recent progress in diffusion based manifold learning and its applications" Abstract | Video
April 5, 2022Simon Foucart (Texas A&M University): "Integrating Observation Errors in Optimal Recovery" Abstract
March 29, 2022Felix Krahmer (Technische Universität München): "The convex geometry of blind deconvolution revisited" Abstract | Video
March 22, 2022Soledad Villar (Johns Hopkins University): "Equivariant machine learning and dimensional analysis" Abstract | Video
March 15, 2022Sinan Gunturk (New York University): "Approximation with one-bit polynomials and one-bit neural networks" Abstract | Video
March 8, 2022Igor Balla (Hebrew University of Jerusalem): "Equiangular lines and regular graphs" Abstract | Video
March 1, 2022Jonathan Jedwab (Simon Fraser University): "Perfect sequence covering arrays" Abstract | Slides | Video
February 22, 2022Sho Suda (National Defense Academy of Japan) "Two topics on equiangular tight frames" Abstract | Video
February 15, 2022Tim Kunisky (Yale University): "Dual bounds for the positive definite functions approach to mutually unbiased bases" Abstract | Video
February 8, 2022Darrin Speegle (Saint Louis University): "Simultaneous Dilation and Translation Tilings of R^n" Abstract | Video
February 1, 2022Henry Adams (Colorado State University): "The topology of projective codes" Abstract | Slides | Video
January 25, 2022Lutz Warnke (University of California San Diego): "The Density of Costas Arrays Decays Exponentially" Abstract | Video
January 18, 2022Bernd Sturmfels (University of California Berkeley and Max Planck Institute for Mathematics in the Sciences Leipzig): "Linear PDE with Constant Coefficients" Abstract | Slides
December 7, 2021Rima Alaifari (ETH Zürich): "(Non-)uniqueness of phase recovery from Gabor and wavelet transform measurements" Abstract | Video
November 30, 2021Dan Edidin (University of Missouri): "Dihedral multi-reference alignment" Abstract | Video | Slides
November 16, 2021Wojciech Czaja (University of Maryland): "Fourier Scattering as Efficient Feature Extraction" Abstract | Video
November 9, 2021Monika Dörfler (Universität Wien): "Structure and Effective Dimensionality of Time Series Data Sets" Abstract
November 2, 2021Alexander Powell (Vanderbilt University): "Dynamical Duals and Error Diffusion" Abstract
October 26, 2021Markus Grassl (International Centre for Theory of Quantum Technologies, University of Gdańsk): "Computing SIC-POVMs using Permutation Symmetries and Stark Units" Abstract | Video | Slides
October 19, 2021Joey Iverson (Iowa State University): "Equiangular lines over finite fields" Abstract | Video | Slides
October 12, 2021Clay Shonkwiler (Colorado State University): "A Lie Algebraic Perspective on Frame Theory" Abstract | Video
October 5, 2021X.Y. Han (Cornell University): "Prevalence of Neural Collapse during the terminal phase of deep learning training" Abstract | Video
September 28, 2021Boumediene Et-Taoui (Université de Haute Alsace): "A survey on complex conference matrices" Abstract | Video | Slides
September 21, 2021Naoki Saito (University of California Davis): "Multiscale Graph Basis Dictionaries" Abstract | Video
September 14, 2021Tom Needham (Florida State University): "Applications of Symplectic Geometry to Frame Theory" Abstract | Video | Slides
September 7, 2021Armenak Petrosyan (Georgia Institute of Technology): "Integral neural networks with weight penalization" Abstract | Video
August 31, 2021Mauro Maggioni (Johns Hopkins University): "Learning Interaction laws in particle- and agent-based systems" Abstract | Video
August 24, 2021Longxiu Huang (University of California Los Angeles): "CUR Decompositions and their Applications" Abstract | Video
August 10, 2021Romanos Diogenes-Malikiosis (Aristotle University of Thessaloniki): "Recent developments in the discrete Fuglede conjecture" Abstract | Slides | Video
August 3, 2021Matt Herman (Fourier Genetics): "Fourier Analysis on the Genome" Abstract | Video | Slides
July 27, 2021Nate Strawn (Georgetown University): "3D Filament Plots from Optimally Smooth 2D Andrew's Plots" Abstract | Slides | Video
July 13, 2021[Summer Student and Postdoc Talks]
Davi Castro-Silva (Universität zu Köln): "Geometrical sets with forbidden configurations" Abstract | Video | Slides
July 6, 2021[Summer Student and Postdoc Talks]
Nathan Lindzey (University of Colorado Boulder): "Discrete Harmonic Analysis on Matchings" Abstract | Video
June 29, 2021Xuemei Chen (University of North Carolina Wilmington): "Frame optimization with projective Riesz kernel" Abstract | Video
June 22, 2021[Summer Student and Postdoc Talks]
Nadiia Derevianko (Universität Göttingen): "Estimation of Signal Parameters by Iterative Rational Approximation" Abstract | Video
June 15, 2021Michael Perlmutter (University of California Los Angeles): "Convolutional Networks on (Directed) Graphs via the Graph Fourier Transform" Abstract | Video | Slides
June 8, 2021Mikhail Ganzhinov (Aalto University): "Infinite families of optimal biangular line packings" Abstract | Video
June 1, 2021[Summer Student and Postdoc Talks]
Joseph Cummings (University of Kentucky): "Phylogenetic Networks" Abstract | Video
May 25, 2021Elina Robeva (University of British Columbia): "Orthogonal and Incoherent Tensor decomposition" Abstract | Video
May 18, 2021Radu Balan (University of Maryland):"Embeddings of Metric Spaces induced by Permutation Groups" Abstract | Video
May 11, 2021Steve Butler (Iowa State University): "Hadamard diagonalizable graphs of small order" Abstract | Video
May 4, 2021Cynthia Vinzant (North Carolina State University): "The geometry of spectrahedra" Abstract | Video | Slides
April 27, 2021Azita Mayeli (City University of New York, the Graduate Center): "Exponential completeness and φ-approximate orthogonality on the unit ball" Abstract
April 20, 2021Marcin Bownik (University of Oregon): "Multiplication-invariant operators and the classification of abelian group frames" Abstract | Video | Slides
April 13, 2021Gary Greaves (Nanyang Technological University): "Real equiangular line systems in low dimensions" Abstract | Video | Slides
April 6, 2021Robert Calderbank (Duke University): "Coherent Noise" Abstract |
March 30, 2021Vignon Oussa (Bridgewater State University): "Why are topics such as differential geometry and representation theory useful to frame theory?" Abstract | Video
March 23, 2021Zilin Jiang (Arizona State University): "Spherical two-distance sets and spectral theory of signed graphs" Abstract " Video
March 16, 2021Daniel Freeman (St Louis University): "Discretizing L_p norms" Abstract | Video
March 9, 2021Keaton Hamm (The University of Texas at Arlington): "Column Selection and You" Abstract | Video
March 2, 2021Ram Zamir (Tel Aviv University): "Asymptotic Frame Theory for Analog Coding" Abstract | Video | Slides
February 23, 2021Joshua A. Grochow (University of Colorado Boulder): "Codes and Expansions in Algorithms for Matrix Multiplication" Abstract | Video | Slides
February 16, 2021Karin Schnass (Universität Innsbruck): "Random submatrices with non-uniformly distributed supports" Abstract | Video
February 9, 2021Eugenio Hernández (Universidad Autónoma de Madrid): "Spaces invariant under unitary representations and the bracket" Abstract | Slides | Video
February 2, 2021Emily J. King (Colorado State University): "A Potpourri of Projective 2-Designs" Abstract | Video | Slides
January 26, 2021Steven Flammia (AWS Center for Quantum Computing): "Ghosts, Necromancy, and Zauner's Conjecture" Abstract | Video
December 8, 2020Chris Heil (Georgia Tech): "Frames, Erasures, and Excess in Infinite Dimensions" Abstract | Video | Slides
December 1, 2020Hartmut Führ (RWTH Aachen): "Frames of translates and the bandwidth intuition" Abstract | Video | Slides
November 17, 2020Philipp Petersen (Universität Wien): "Functions with structured singularities" Abstract | Video
November 10, 2020Alex Cloninger (University of California at San Diego): "Fast Statistical and Geometric Distances Between Families of Distributions" Abstract | Video
November 3, 2020Gerlind Plonka-Hoch (Universität Göttingen): "Optimal Rank-1 Hankel Approximation of Matrices" Abstract | Video | Slides
October 27, 2020Akram Aldroubi (Vanderbilt University): "Transport transforms for data analysis and machine learning" Abstract | Video
October 20, 2020Dustin G. Mixon (The Ohio State University): "Symmetry and optimality in codes" Abstract | Video
October 13, 2020John J. Benedetto (University of Maryland): "Spectral super-resolution and unique extensions for complex measures" Abstract | Video
October 6, 2020Shahaf Nitzan (Georgia Tech): "A few remarks on 'good' exponential Riesz bases" Abstract
September 29, 2020Boris Bukh (Carnegie Mellon University): "Ranks of matrices with few distinct entries" Abstract | Video
September 22, 2020Eric Weber (Iowa State University): "Conjugate Phase Retrieval in Paley-Wiener Space" Abstract | Video | Slides
September 15, 2020Bill Martin (Worcester Polytechnic Institute): "Schoenberg's Theorem and Association Schemes" Abstract | Video | Slides
September 8, 2020Hanmeng (Harmony) Zhan (York University): "DRACKNs and their applications in quantum information" Abstract | Video
September 1, 2020Chris Manon (University of Kentucky): "Spaces of Eigenvalues" Abstract | Video
August 25, 2020Frank Vallentin (Universität zu Köln): "Coloring the Voronoi tessellation of lattices" Abstract | Video
August 18, 2020David Gross (Universität zu Köln): "Representation theory of the Clifford group, with sundry applications" Abstract | Video
August 11, 2020Kasso Okoudjou (Tufts University): "The search for universal minimizers of p-frame potentials" Abstract | Video
August 4, 2020 Marcus Appleby (University of Sydney): "SICs and Number Theory" Abstract | Video
July 28, 2020Matt Fickus (Air Force Institute of Technology): "Mutually Unbiased Equiangular Tight Frames" Abstract | Slides | Video
July 21, 2020Vern Paulsen (University of Waterloo): "Entanglement Breaking Maps and Zauner's Conjecture" Abstract | Video
July 14, 2020Afonso S. Bandeira (ETH Zürich): "Hardness of refuting coloring in random graphs and quiet computational planting" Abstract | Video
July 7, 2020Bernhard Bodmann (University of Houston): "Polynomial embeddings as cheat codes for a real Game of Sloanes" Abstract | Video
June 30, 2020Pete Casazza (University of Missouri): "Two Distance Sets" Abstract | Video
June 23, 2020Alex Iosevich (University of Rochester): "On point configurations and frame theory" Abstract | Video | Slides
June 9, 2020Gene Kopp (University of Bristol): "SIC-POVM existence and the Stark conjectures" Abstract | Video
June 2, 2020Jameson Cahill (New Mexico State University): "Optimal Parseval Frames" Abstract | Video
May 26, 2020Chris Cox (Carnegie Mellon University / Iowa State University): "Nearly Orthogonal Vectors" Abstract | Video
May 19, 2020Hans Parshall (Ohio State University / Western Washington University): "Optimal Line Packings" Abstract | Video