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DTSTART;TZID=America/New_York:20261109T163000
DTEND;TZID=America/New_York:20261109T173000
DTSTAMP:20261029T140252Z
CREATED:20260729T200854Z
LAST-MODIFIED:20261029T140252Z
UID:10004032-1794241800-1794245400@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Unitary extended topological field theories and higher Hermitian objects
DESCRIPTION:Colloquium \nSpeaker: Lukas Müller (LMU Munich) \nTitle: Unitary extended topological field theories and higher Hermitian objects \nAbstract: Mathematically\, topological field theories study the representation theory of manifolds undercutting and gluing. Extended topological field theories take this idea a step further by allowing one to cut manifolds in multiple directions\, leading to a formulation in terms of higher category theory. It is an open problem to give a complete definition and description of unitary representations of manifolds as extended topological field theories. \nIn my talk\, I will explain some recent progress towards the definition and classification of unitary extended topological field theories. This is based on a categorification of the concept of a Hermitian object in a rigid symmetric monoidal category\, introduced by Freed and Hopkins in the study of non-extended unitary topological field theories. \nThe talk is based on several joint works involving (in part) Giovanni Ferrer\, Brett Hungar\, Theo Johnson-Freyd\, Cameron Krulewski\, Nivedita\, David Penneys\, David Reutter\, Claudia Scheimbauer\, Luuk Stehouwer\, and Chetan Vuppulury\, as well as ongoing work with Theo Johnson-Freyd\, Cameron Krulewski\, and Luuk Stehouwer. \n  \n  \n\nTo subscribe or unsubscribe to the colloquium mailing list\, please visit this link.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/colloquium-11926/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Colloquium
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/2026/07/CMSA-Colloquium-11.9.2026.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20261123T163000
DTEND;TZID=America/New_York:20261123T173000
DTSTAMP:20261013T151255Z
CREATED:20260729T200958Z
LAST-MODIFIED:20261013T151255Z
UID:10004034-1795451400-1795455000@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Colloquium
DESCRIPTION:Colloquium \nSpeaker: Ewain Gwynne\, U Chicago \n  \n  \n  \n\nTo subscribe or unsubscribe to the colloquium mailing list\, please visit this link.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/colloquium-112326/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Colloquium
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20261130T163000
DTEND;TZID=America/New_York:20261130T173000
DTSTAMP:20261102T133025Z
CREATED:20260729T200924Z
LAST-MODIFIED:20261102T133025Z
UID:10004033-1796056200-1796059800@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Snake graphs and q-deformed real numbers
DESCRIPTION:Colloquium \nSpeaker: James Propp (UMass Lowell) \nTitle: Snake graphs and q-deformed real numbers \nAbstract: I’ll present a statistical-mechanical construction of q-deformed real numbers [[x]]_q\, inspired by the q-deformed rational numbers [x]_q of Morier-Genoud and Ovsienko. The new construction admits two equivalent formulations: one in terms of random filters in snake posets and the other in terms of random dimer covers of snake graphs. \nI’ll begin with a combinatorial approach to Stern’s diatomic series and the Calkin–Wilf bijection via finite snake graphs\, and then construct q-deformed rational numbers by introducing an activity parameter q into the model. I extend from q-deformed rationals to q-deformed reals by passing from finite to infinite snake graphs; the main technical step is to show that the associated limiting probability measures are well defined. \nThe resulting q-deformation [[x]]_q satisfies [[x]]_1 = x for all x>0. There’s evidence that\, wherever both [x]_q and [[x]]_q are defined\, [[x]]_q = q [x]_q. For more details\, see arXiv:2607.14332. \n  \n\nTo subscribe or unsubscribe to the colloquium mailing list\, please visit this link.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/colloquium-111626/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Colloquium
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/2026/07/CMSA-Colloquium-11.16.2026.docx-1-scaled.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20261130T163000
DTEND;TZID=America/New_York:20261130T173000
DTSTAMP:20261013T151306Z
CREATED:20260729T201026Z
LAST-MODIFIED:20261013T151306Z
UID:10004035-1796056200-1796059800@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Colloquium
DESCRIPTION:Colloquium \n  \n  \n  \n\nTo subscribe or unsubscribe to the colloquium mailing list\, please visit this link.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/colloquium-113026/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Colloquium
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