Home /  Geometry and Representation Theory of Tensors for Computer Science, Statistics, and other areas

Summer Graduate School

Geometry and Representation Theory of Tensors for Computer Science, Statistics, and other areas July 07, 2008 - July 18, 2008
Parent Program: --
Location: Baker Board Room
Organizers J.M. Landsberg (Texas A&M), Lek-Heng Lim (UC Berkeley) and Jason Morton (UC Berkeley)
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Description Questions in computational complexity, statistical learning theory, signal processing, scientific data analysis, and other areas have recently been recast in terms of geometry and representation theory. Among them are: the complexity of matrix multiplication, Valiant's approach to P=NP, measures of entanglement in quantum information theory, matchgates in computer science, graphical models in statistical learning theory, the study of phylogenetic invariants, independent component analysis and other multilinear data analytic techniques in bioinformatics, signal processing, and spectroscopy. The geometric perspective allows one to understand the questions in a more general mathematical context. It explains known results in terms of standard theorems in geometry and helps to advance the relevant areas. The goals of this workshop are twofold: To introduce the relevant geometry and representation theory and to present and discuss open questions from the relevant areas that we believe could be resolved by workshop participants. We will introduce the problems that lead to varieties in spaces of tensors and cover the basic geometry and representation theory needed to study them. By the middle of the second week we expect to begin projects working on open questions. The preliminary schedule for the workshop is available at http://docs.google.com/View?docid=dcnmtggh_29px7qd3cw. For more advanced participants, there will be a follow-up research workshop at the American Institute of Mathematics (AIM) the week after the graduate workshop. Information on the research workshop is available at http://www.aimath.org/ARCC/workshops/repnsoftensors.html. If you are a student who has not been nominated for this workshop by one of our Academic Sponsors, please e-mail coord@msri.org for information about registration.
Keywords and Mathematics Subject Classification (MSC)
Primary Mathematics Subject Classification No Primary AMS MSC
Secondary Mathematics Subject Classification No Secondary AMS MSC
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For information about recommended hotels for visits of under 30 days, visit Short-Term Housing. Questions? Contact coord@slmath.org.

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Schedule, Notes/Handouts & Videos
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Jul 07, 2008
Monday
09:15 AM - 10:15 AM
  Complexity of matrix multiplication, an overview of Ch. 2 including tensors, rank of tensors, and wiring diagrams.
Joseph Landsberg (Texas A&M International University)
10:15 AM - 11:15 AM
  Algebraic varieties § 3.1, 3.2. Basic definitions from algebraic geometry: projective space, variety, ideal, Zariski topology. Segre, Veronese, and other examples of varieties. Graphical models and motivating examples in statistics and information t
Jason Morton (Pennsylvania State University)
11:30 AM - 12:30 PM
  Tensor approximations
Lek-Heng Lim (University of Chicago)
Jul 08, 2008
Tuesday
09:00 AM - 10:00 AM
  Finish Ch. 2: skew-symmetric tensors, equations for rank at most r linear mappings, border rank, decomposing V^{\ot 3}., G-modules, isotypic components. § 4.1,2 Representations, Schur's Lemma, G-modules and decomposing spaces of tensors
Jason Morton (Pennsylvania State University)
10:15 AM - 11:15 AM
  § 3.3,4,5,6 Tangent spaces to varieties, joins, cones, secant varieties, their dimension, Terracini's lemma.
Joseph Landsberg (Texas A&M International University)
11:30 AM - 12:30 PM
  Notions of tensor ranks: rank, border rank, multilinear rank, nonnegative rank
Vin de Silva
02:00 PM - 03:00 PM
  What is quantum information theory?
David Gross
Jul 09, 2008
Wednesday
09:00 AM - 10:00 AM
  Finish Chap 3 - Terracini's lemma cont'd and applications to computing the dimension of secant varieties. The geometric definition of border rank, projective second fundamental form.
Joseph Landsberg (Texas A&M International University)
10:15 AM - 11:15 AM
  § 4.3,4,5 - Representations of the symmetric group, Young diagrams, Young symmetrizers and wiring diagrams. Using these tools to decompose V^{\otimes d} as a GL(V) module. Schur-Weyl Duality.
Jason Morton (Pennsylvania State University)
11:30 AM - 12:30 PM
  Conditioning, computations, applications
Lek-Heng Lim (University of Chicago)
Jul 10, 2008
Thursday
09:00 AM - 10:00 AM
  Toric varieties, toric ideals, moment map, exponential families.
Jason Morton (Pennsylvania State University)
10:15 AM - 11:15 AM
  § 4.6,7,8 Highest weight vectors, bases of highest weight space. Ideals of Segre, Veronese varieties and homogeneous varieties in general, decomposing S^d(A_1\otimes \cdots \otimes A_n), characters.
Joseph Landsberg (Texas A&M International University)
11:30 AM - 12:30 PM
  Constructibility of the set of tensors of a given rank
Vin de Silva
02:00 PM - 03:00 PM
  Phylogenetic algebraic geometry
Luis David Garcia Puente (Colorado College)
Jul 11, 2008
Friday
09:00 AM - 10:00 AM
  finish Ch 4 (Littlewood-Richardson rule and other handy formulas, more decompositions of spaces of tensors)
Jason Morton (Pennsylvania State University)
10:15 AM - 11:15 AM
  § 5.1-5.3 Equations for secant varieties I: special Segre varieties, subspace varieties, flattenings
Joseph Landsberg (Texas A&M International University)
11:30 AM - 12:30 PM
  Hyperdeterminants and optimal approximability
Vin de Silva
02:00 PM - 03:00 PM
  What are graph states?
David Gross
Jul 14, 2008
Monday
09:00 AM - 10:00 AM
  § 5.4, 5.5 Equations II: inheritance, and prolongation
Jason Morton (Pennsylvania State University)
10:15 AM - 11:15 AM
  § 5.6 Equations III: Strassen's equations and variants
Joseph Landsberg (Texas A&M International University)
11:30 AM - 12:30 PM
  Uniqueness of tensor decomposition, direct sum conjecture
Vin de Silva
02:00 PM - 03:00 PM
  Non-commutative harmonic analysis in machine learning
Risi Kondor (University of Chicago; Flatiron Institute)
Jul 15, 2008
Tuesday
09:00 AM - 10:00 AM
  § 6.1,6.2,6.6,6.7 The Alexander-Hirshowitz theorem and dimensions of secant varieties of Segre varieties
Joseph Landsberg (Texas A&M International University)
10:15 AM - 11:15 AM
  Ch 7. An algorithm for explicitly writing down polynomials in a given submodule of the space of polynomials. Further combinatorics of Young tableaux. Working with tensors in factored vs. expanded form.
Jason Morton (Pennsylvania State University)
11:30 AM - 12:30 PM
  Ch 8: Rank vs border rank of tensors and symmetric tensors
Joseph Landsberg (Texas A&M International University)
02:00 PM - 03:00 PM
  The variety of principal minors of symmetric matrices
Luke Oeding (Auburn University)
Jul 16, 2008
Wednesday
09:00 AM - 10:00 AM
  (a) general statements on linear mixtures of random variables, (b)cumulants, (c) tensors
Pierre Comon
10:15 AM - 11:15 AM
  What do the words "ACM", "Gorenstein", and " rational singularites" mean and why are these properties useful?
Jerzy Weyman (Jagiellonian University)
11:30 AM - 12:30 PM
  Nonnegative hypermatrices, symmetric tensors
Lek-Heng Lim (University of Chicago)
Jul 17, 2008
Thursday
09:00 AM - 10:00 AM
  (d) the invertible case: Independent Component Analysis - optimization criteria and some numerical algorithms
Pierre Comon
10:15 AM - 11:15 AM
  Introduction to the study of G-varieties via desingularizations by homogeneous vector bundles
Jerzy Weyman (Jagiellonian University)
11:30 AM - 12:30 PM
  Ch 9: Spaces of tensors admitting normal forms
Joseph Landsberg (Texas A&M International University)
Jul 18, 2008
Friday
09:00 AM - 10:00 AM
  (e) the UDM case: some selected statistical blind identification approaches, all involving tensors. Local identifiability and numerical algorithms (including BIOME and FOOBI).
Pierre Comon
10:15 AM - 11:15 AM
  Induction for the rank of tensors
Giorgio Ottaviani
11:30 AM - 12:30 PM
  Student Lecture
02:00 PM - 03:00 PM
  The Alexander-Hirschowitz theorem
Giorgio Ottaviani