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DTSTART;TZID=America/New_York:20251027T150000
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DTSTAMP:20260427T132849
CREATED:20250924T183029Z
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SUMMARY:de Rham Theory in Derived Differential Geometry
DESCRIPTION:Quantum Field Theory and Physical Mathematics Seminar \nSpeaker: Grigorii Taroian\, U Toronto \nTitle: de Rham Theory in Derived Differential Geometry \nAbstract: In the talk\, I will describe recent progress in building a version of de Rham theory for derived manifolds and derived differentiable stacks.\nDerived differential geometry is a nascent field applying techniques from derived algebraic geometry to the study of spaces with smooth structures. As such\, it serves as a natural home for studying objects arising in BV formalism. For instance\, concepts such as critical loci of action functionals or their quotients by gauge actions can be naturally interpreted as derived differentiable stacks.\nIn our work\, we build a version of de Rham theory for these spaces and prove a version of the de Rham isomorphism. Due to the highly singular nature of all objects involved\, developing such a theory is significantly more challenging than in the usual differential geometry\, and thus\, we construct our formalism with inspiration from algebraic geometry rather than classical differential topology. As a main application of the developed theory\, we obtain a version of the comparison morphism between de Rham and constant sheaf cohomology arising from the corresponding map of stacks. This should enable further developments\, with a view towards a fully-fledged theory of shifted symplectic structures for derived differentiable stacks.\nThe talk is based on a preprint of the same name\, arXiv:2505.03978.
URL:https://cmsa.fas.harvard.edu/event/qft_102725/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Quantum Field Theory and Physical Mathematics
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-QFT-and-Physical-Mathematics-10.27.25-scaled.png
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DTSTART;TZID=America/New_York:20251027T163000
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CREATED:20250911T192619Z
LAST-MODIFIED:20250911T193132Z
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SUMMARY:Rigidity\, expansion and polytopes
DESCRIPTION:Colloquium \nSpeaker: Eran Nevo (Hebrew University of Jerusalem) \nTitle: Rigidity\, expansion and polytopes \nAbstract: Given a graph G and an embedding of its vertices in R^d\, what continuous motions of the vertices preserve all edge lengths? Clearly all motions induced by an isometry of R^d do\, these are the trivial motions; are there any others? If the answer is NO for all (equivalently\, for one) generic embedding\, G is called d-rigid. \nWhat are the d-rigid graphs? \nThis problem has been extensively studied since the 70s\, and is still widely open for d≥3. It is studied mainly from algebraic geometry and combinatorial points of view. Variants of it\, especially in dimensions 2 and 3\, are of importance also beyond mathematics\, e.g. in structural engineering\, computational biology and more. \nI will focus on a quantitative version of rigidity via spectral analysis of the related stiffness matrix\, including the construction of “rigidity expanders”\, generalizing expander graphs. Higher dimensional notions of rigidity and of stiffness matrices\, and their relation to the study of polytopes\, will be addressed too.
URL:https://cmsa.fas.harvard.edu/event/colloquium_102725/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Colloquium
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Colloquium-10.27.2025.png
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