PERIMETER INSTITUTE RECORDED SEMINAR ARCHIVE
 | On the classification of topological phases Speaker(s): Theo Johnson-Freyd
Abstract: There is a rich interplay between higher algebra (category theory, algebraic topology) and condensed matter. I will describe recent mathematical results in the classification of gapped topological phases of matter. These results allow powerful techniques from stable homotopy theory and higher catego... read more
Date: 01/06/2020 - 11:00 am
Series: Colloquium
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 | Gapped condensation in higher categories Speaker(s): Theo Johnson-Freyd
Abstract: Idempotent (aka Karoubi) completion is used throughout mathematics: for instance, it is a common step when building a Fukaya category. I will explain the n-category generalization of idempotent completion. We call it "condensation completion" because it answers the question of classifying the gapped... read more
Date: 17/03/2020 - 12:30 pm
Series: Mathematical Physics
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 | A deformation invariant of 1+1D SQFTs Speaker(s): Theo Johnson-Freyd
Abstract: The elliptic genus is a powerful deformation invariant of 1+1D SQFTs: if it is nonzero, then it protects the SQFT from admitting a deformation to one with spontaneous supersymmetry breaking. I will describe a "secondary" invariant, defined in terms of mock modularity, that goes beyond the elliptic g... read more
Date: 14/01/2020 - 2:30 pm
Series: Quantum Fields and Strings
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 | The Cohomology of Groups (Johnson-Freyd/Guo) - Lecture 11 Speaker(s): Theo Johnson-Freyd, Meng Guo
Abstract:
Date: 13/12/2019 - 1:00 pm
Collection: The Cohomology of Groups (Johnson-Freyd/Guo)
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 | The Cohomology of Groups (Johnson-Freyd/Guo) - Lecture 10 Speaker(s): Meng Guo, Theo Johnson-Freyd
Abstract:
Date: 04/12/2019 - 10:00 am
Collection: The Cohomology of Groups (Johnson-Freyd/Guo)
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 | The Cohomology of Groups (Johnson-Freyd/Guo) - Lecture 9 Speaker(s): Meng Guo, Theo Johnson-Freyd
Abstract:
Date: 27/11/2019 - 10:00 am
Collection: The Cohomology of Groups (Johnson-Freyd/Guo)
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 | The Cohomology of Groups (Johnson-Freyd/Guo) - Lecture 8 Speaker(s): Meng Guo, Theo Johnson-Freyd
Abstract:
Date: 20/11/2019 - 10:00 am
Collection: The Cohomology of Groups (Johnson-Freyd/Guo)
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 | The Cohomology of Groups (Johnson-Freyd/Guo) - Lecture 7 Speaker(s): Meng Guo, Theo Johnson-Freyd
Abstract:
Date: 13/11/2019 - 10:00 am
Collection: The Cohomology of Groups (Johnson-Freyd/Guo)
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 | The Cohomology of Groups (Johnson-Freyd/Guo) - Lecture 6 Speaker(s): Meng Guo, Theo Johnson-Freyd
Abstract:
Date: 06/11/2019 - 10:00 am
Collection: The Cohomology of Groups (Johnson-Freyd/Guo)
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 | The Cohomology of Groups (Johnson-Freyd/Guo) - Lecture 5 Speaker(s): Meng Guo, Theo Johnson-Freyd
Abstract:
Date: 30/10/2019 - 10:00 am
Collection: The Cohomology of Groups (Johnson-Freyd/Guo)
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 | The Cohomology of Groups (Johnson-Freyd/Guo) - Lecture 4 Speaker(s): Meng Guo, Theo Johnson-Freyd
Abstract:
Date: 23/10/2019 - 10:00 am
Collection: The Cohomology of Groups (Johnson-Freyd/Guo)
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 | The Cohomology of Groups (Johnson-Freyd/Guo) - Lecture 3 Speaker(s): Meng Guo, Theo Johnson-Freyd
Abstract:
Date: 16/10/2019 - 10:00 am
Collection: The Cohomology of Groups (Johnson-Freyd/Guo)
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 | The Cohomology of Groups (Johnson-Freyd/Guo) - Lecture 2 Speaker(s): Meng Guo, Theo Johnson-Freyd
Abstract:
Date: 09/10/2019 - 10:00 am
Collection: The Cohomology of Groups (Johnson-Freyd/Guo)
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 | The Cohomology of Groups (Johnson-Freyd/Guo) - Lecture 1 Speaker(s): Meng Guo, Theo Johnson-Freyd
Abstract:
Date: 02/10/2019 - 10:00 am
Collection: The Cohomology of Groups (Johnson-Freyd/Guo)
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 | TA Session: 0d QFT and Feynman diagrams Speaker(s): Theo Johnson-Freyd
Abstract:
Date: 17/06/2019 - 4:00 pm
Collection: QFT for Mathematicians
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 | Koszul Duality Seminar Speaker(s): Theo Johnson-Freyd
Abstract:
Being held in the Skyroom. Date: 12/12/2018 - 2:30 pm
Series: Cosmology & Gravitation
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 | Welcome and Opening Remarks Speaker(s): Theo Johnson-Freyd, Andre Henriques
Abstract:
Date: 13/08/2018 - 9:00 am
Collection: Higher Algebra and Mathematical Physics
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 | Higher algebraic closures and phases of matter Speaker(s): Theo Johnson-Freyd
Abstract:
Date: 15/01/2018 - 2:00 pm
Series: Mathematical Physics
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 | Moonshine, topological modular forms, and 576 fermions. Speaker(s): Theo Johnson-Freyd
Abstract:
I will report on progress understanding the 576-fold periodicity in TMF in terms of conformal field theoretic constructions. Sporadic finite groups and their cohomology will play a role. Date: 22/09/2016 - 1:30 pm
Series: Mathematical Physics
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