David Penneys
Professor of Mathematics at The Ohio State University
Office: Room 752 Math Tower
Email: penneys (dot) 2 (at) osu (dot) edu

dsp in la

About me:

I received my Ph.D. from the University of California, Berkeley in 2012 studying subfactor theory under the supervision of Vaughan Jones. I completed a 2 year postdoc from 2012-2014 at the University of Toronto under the supervision of Dror Bar-Natan and George Elliott. From 2014-2016, I was an Assistant Adjunct Professor at UCLA. I study quantum symmetries via operator algebras and tensor categories with applications to quantum many-body systems, especially topologically ordered phases of matter. In nature and the physical sciences, symmetry is described by group actions, where an object X has G-symmetry if G is a collection of self-maps closed under composition and inversion. Typically these self maps are morphisms in some category, such as topological spaces, vector spaces, or algebras, and G acts via a map to End(X). Quantum mathematical objects naturally live in higher categories, where the collections of self-maps End(X) form higher monoidal categories. Thus higher groups and higher monoidal categories act on X via monoidal functors to End(X), allowing for richer non-invertible/categorical/quantum symmetries.

Here is a copy of my Curriculum Vitae.
Here is a link to my articles on the arXiv.
Here is a link to my Google Scholar profile.

Here is a link to a book in progress with Giovanni Ferrer and Kyle Kawagoe called Unitary Quantum Symmetries Lite.


Mathematics Teaching


Graduate students and postdocs

Current graduate students and their dissertation work Current postdocs Former PhD students
  • David GREEN
    • thesis: Tannakian formalism for compact semisimple 2-categories
    • 2025-28: postdoc at North Carolina State University with Corey JONES
  • Quan CHEN
    • thesis: Higher symmetries in operator algebras
    • 2023-26: postdoc at Vanderbilt University with Dietmar BISCH
  • Zachary DELL
    • thesis: Characterization of unitary braided-enriched monoidal categories
    • 2022-: ESports Rocket League coach at Illinois State University
  • Peter HUSTON
    • thesis: Tensor category constructions in topological phases of matter
    • 2022-25: postdoc at Vanderbilt University with Dietmar BISCH
    • 2025-27: Research Fellow at the University of Leeds working on the EPSRC grant "Combinatorial Representation Theory: Discovering the Interfaces of Algebra with Geometry and Topology."
  • Roberto HERNANDEZ PALOMARES
Former postdocs

Mathematics Research

Peer reviewed journal articles Peer reviewed conference proceedings
  • Corey Jones and David Penneys. Q-systems and compact W*-algebra objects. Topological phases of matter and quantum computation, 63--88, Contemp. Math., 747, Amer. Math. Soc., Providence, RI, 2020. [arXiv:1707.02155, DOI:10.1090/conm/747/15039]
  • Zhengwei Liu, Scott Morrison, and David Penneys. Lifting shadings on symmetrically self-dual subfactor planar algebras. Topological phases of matter and quantum computation, 51--61, Contemp. Math., 747, Amer. Math. Soc., Providence, RI, 2020. [arXiv:1709.05023, DOI:10.1090/conm/747/15038]
  • Zhengwei Liu and David Penneys. The generator conjecture for $3^G$ subfactor planar algebras. Proceedings of the 2014 Maui and 2015 Qinhuangdao conferences in honour of Vaughan F. R. Jones' 60th birthday, 344--366, Proc. Centre Math. Appl. Austral. Nat. Univ., 46, Austral. Nat. Univ., Canberra, 2017. [arXiv:1507.04794, available online here]
Additional conference proceedings
  • David Penneys (joint work with Corey Jones, Pieter Naaijkens, and Daniel Wallick). Holography for bulk-boundary topological order. 2025. To appear Oberwolfach Reports. [PDF]
  • David Penneys (joint work with Marcel Bischoff, Ian Charlesworth, Samuel Evington, Luca Giorgetti, and André Henriques). Modular distortion for II_1 multifactor bimodules. 2019. Oberwolfach Reports. [DOI:10.4171/OWR/2019/49, PDF]
  • David Penneys (joint work with André Henriques and James Tener). Planar algebras in modular tensor categories. 2015. Oberwolfach Reports. [DOI:10.4171/OWR/2015/16, PDF]
arXiv preprints
  • Scott Morrison, David Penneys, and Julia Plavnik. Completion for braided enriched monoidal categories. 2018. [arXiv:1809.09782]
  • André Henriques, David Penneys, and James Tener. Classification of finite depth objects in bicommutant categories via anchored planar algebras. 2023. [arXiv:2307.13822]
  • Giovanni Ferrer, Brett Hungar, Theo Johnson-Freyd, Cameron Krulewski, Lukas Muller, Nivedita, David Penneys, David Reutter, Claudia Scheimbauer, Luuk Stehouwer, and Chetan Vuppulury. Dagger n-categories. 2024. [arXiv:2403.01651]
  • Quan Chen, Giovanni Ferrer, Brett Hungar, David Penneys, and Sean Sanford. Manifestly unitary higher Hilbert spaces. 2024. [arXiv:2410.05120]
  • André Henriques, Nivedita, and David Penneys. Complete W*-categories. 2024. [arXiv:2411.01678]
  • Thibault D. Décoppet, Peter Huston, Theo Johnson-Freyd, Dmitri Nikshych, David Penneys, Julia Plavnik, David Reutter, and Matthew Yu. The classification of fusion 2-categories. 2024. [arXiv:2411.05907]
  • Pavel Etingof and David Penneys. Rigidity of non-negligible objects of moderate growth in braided categories. 2024. [arXiv:2412.17681]
  • Corey Jones, Pieter Naaijkens, and David Penneys. Holography for bulk-boundary local topological order. 2025. [arXiv:2506.19969]
Dissertation
  • David Penneys. Planar structure for inclusions of finite von Neumann algebras. 2012. [pdf]


Conference and seminar talks

2025 2024
  • ECOAS at NCSU 11/9-10. Superselection sectors for posets of von Neumann algebras
  • Vanderbilt University 9/13. Subfactor seminar. Subfactor techniques in topological order
  • Vanderbilt University 9/12. Colloquium. Local Topological Quantum Codes
  • SLMath Quantum Symmetries Reunion 7/15. Seminar talk -- 3Hilb
  • SLMath Quantum Symmetries Reunion 7/15. Lightning talk -- Boundary algebras for enriched Levin-Wen models
  • ICMS workshop on Categorical symmetries in Quantum Field Theory 10/9-13. Levin-Wen is a gauge theory.
  • North Carolina State University 3/28. Corey Jones' research group seminar. What is the toric code?
2023
  • UCSD Functional Analysis Seminar 10/17. An operator algebraic axiomatization of local topological order.
  • ICMS workshop on Topological Quantum Computation 10/9-13. Local topological order and boundary algebras. [video]
  • Purdue Operator Algebras Seminar 9/12. An operator algebraic axiomatization of local topological order.
  • Yasu Festa 60 7/24-28. Local topological order and boundary algebras. [video]
  • Purdue University 6/17. GOALS culminating workshop What is topological order?
  • Zoom workshop Dagger higher categories 6/12. Some subtleties about unitary multitensor categories
  • UM Dearborn 5/25. REU speaker. What is topological order?
  • Vanderbilt NCGOA on von Neumann algebras 5/8-11. Local topological order and boundary algebras. [Unable to attend; talk given by Daniel Wallick]
2022 2021 2020 2019
  • Oberwolfach workshop on Subfactors and their applications 10/28-11/1 Modular distortion for II_1 multifactor bimodules
  • University of Virginia 9/10. Distortion for II_1 multifactor bimodules
  • Vanderbilt NCGOA 5/3-9. G-graded extensions of braided enriched fusion categories
  • AMS Joint Meetings 1/16. Special Session on Hopf algebras and tensor categories. The module embedding theorem. [Beamer slides]
2018
  • UCLA 11/15. Functional analysis seminar. The maximal atlas of the Extended Haagerup subfactor
  • GPOTS, Miami University (Ohio) 5/29-6/2. Plenary speaker. The maximal atlas of the extended Haagerup subfactor planar algebra
  • University of Delaware 3/23. Analysis Seminar. Classifying small quantum symmetries
  • Santa Clara University 3/13. Colloquium. Planar algebras and evaluation algorithms
  • UC Berkeley 3/12. Probabilistic Operator Algebras Seminar. Standard invariants for discrete subfactors
  • Texas A&M 1/30. Linear Analysis Seminar. Standard invariants for discrete subfactors
  • Texas A&M 1/30. Algebra Seminar. Exotic fusion categories: EH3 exists!
2017 2016 2015 2014
  • UC San Diego 12/4. The 2D2 subfactor
  • UC Davis Mathematical Physics & Probability seminar 10/29. Applications of subfactors and fusion categories to mathematical physics [Beamer slides]
  • USC Hopf working seminar 10/14. Planar algebras, Hopf algebras, and fusion categories
  • UCLA Workshop on von Neumann algebras and ergodic theory 9/22-26. Classifying small index subfactors, [Beamer slides]
  • Stanford University 8/22. Planar algebras and evaluation algorithms
  • AMS MRC on Mathematics of Quantum Phases of Matter and Quantum Information 6/24-30. Ostrik's classification of rank 3 pivotal fusion categories
  • GPOTS, Kansas State University 5/27-31. Half hour plenary speaker. Classifying small index subfactors [Beamer slides]
  • Vanderbilt NCGOA 5/2-8. Mini course on Introduction to subfactors. [course notes (first draft), written notes used during lecture, notes on other talks]
  • Vanderbilt 4/25. Classifying small index subfactors [notes]
  • Duke University 4/8. Planar algebras and evaluation algorithms
  • NC State University 4/7. Planar algebras and evaluation algorithms
  • University of New South Wales 3/17. 1-supertransitive subfactors with index at most 6.2
  • The Australian National University 3/11. 1-supertransitive subfactors with index at most 6.2 [notes]
  • UC Riverside 2/27 (Colloquium). Classifying small index subfactors [Beamer slides]
  • UC Davis 1/6. Exotic fusion categories
2013
  • UC Berkeley 11/8. Free graph algebras and GJS C*-algebras
  • UC San Diego 11/7. 1-supertransitive subfactors with index at most 6.2
  • Subfactors in Maui 7/15. Chirality and principal graph obstructions
  • Canadian Annual Symposium on Operator Algebras and Their Applications (COSy) 5/27. Subfactors of index 3+\sqrt{5} [Beamer slides]
  • Institut de Mathematiques de Bourgogne - workshop on fusion categories 5/21-3. Fusion categories between C \boxtimes D and C * D (with applications to subfactors at index 3+\sqrt{5}) [Beamer slides]
  • Northwestern University 4/24. Subfactors of index 3+\sqrt{5}
  • Loyola University 4/17. Planar algebras
  • University of Waterloo 4/5. GJS C*-algebras
  • University of Tokyo 3/12. Constructing subfactors with jellyfish
  • The Australian National University 2/5. Planar algebra
2012
  • Western University 12/10. Constructing subfactors with jellyfish
  • Univrtsity of Michigan, Dearborn colloquium 12/7. Planar algebra
  • UC San Diego 11/13. Constructing subfactors with jellyfish
  • UC Santa Barbara 11/13. Constructing subfactors with jellyfish
  • ECOAS 10/7. Constructing subfactors with the jellyfish algorithm [Beamer slides]
  • Subfactors in Maui 7/16. Spokes, jellyfish, trains, and tails
  • UCLA 6/6. Jellyfish, trains, and principal graph stability
  • UC Santa Barbara 1/31. Automated jellyfish
2011
  • Purude ECOAS 10/15. Infinite index subfactors and the GICAR algebras [Beamer slides]
  • Subfactors in Maui 7/18. Infinite index
  • AMS Joint Meetings, New Orleans 1/8. Eliminating weeds and vines in the classification of subfactors to index 5 [Beamer slides]
2010
  • University of Tokyo operator algebras seminar 7/8. Killing weeds with annular multiplicities *10
  • Kyushu University operator algebras seminar 7/26. Killing weeds with annular multiplicities *10
  • Vanderbilt NCGOA 5/11. The embedding theorem for finite depth subfactor planar algebras [Beamer slides]
2009
  • IMSC colloquium 2/26. Categories and pictures
  • GWU topology seminar 1/12. Examples of planar algebras
2008
  • GWU analysis seminar 3/25. Planar algebras and knot polynomials
Here is a pdf file of all abstracts of conference and seminar talks I have given from 2007-present.


Conferences and seminars organized


International and national conferences Microconferences Seminars
  • Quantum algebra seminar at the Fields Institute Fall 2013 - Spring 2014 [talk abstracts]
  • Subfactor seminar at UC Berkeley Fall 2009 - Spring 2012
  • Student subfactor seminar at UC Berkeley Spring 2008 - Fall 2009


Surveys, expository articles, and miscellaneous


last modified: 2025/9/3