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BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20231201T153000
DTEND;TZID=Europe/Berlin:20231201T170000
DTSTAMP:20260531T184419
CREATED:20231016T110225Z
LAST-MODIFIED:20231121T073143Z
UID:6694-1701444600-1701450000@crc326gaus.de
SUMMARY:Wonderful compactification over an arbitrary base scheme
DESCRIPTION:Seminar on Arithmetic Geometry \nWonderful compactifications of adjoint reductive groups over an algebraically closed field play an important role in algebraic geometry and representation theory. In this talk\, we will construct an equivariant compactification for adjoint reductive groups over arbitrary base schemes\, which parameterize classical wonderful compactifications of De Concini and Procesi as geometric fibers. Our construction is based on a variant of the Artin–Weil method of birational group laws. In particular\, our construction gives a new intrinsic construction of wonderful compactifications. If time permits\, we will also discuss several applications of our compactification in the study of torsors under reductive group schemes. \nShang Li (Paris-Saclay University) \nZoom (635 7328 0984\, Password: smallest six digit prime).
URL:https://crc326gaus.de/event/tba-84/
LOCATION:Darmstadt\, Room 401 and Zoom\, Schlossgartenstraße 7\, Darmstadt\, 64289\, Germany
CATEGORIES:GAUS-Seminar
ORGANIZER;CN="Sabrina Pauli":MAILTO:pauli@mathematik.tu-darmstadt.de
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20231205T153000
DTEND;TZID=Europe/Berlin:20231205T170000
DTSTAMP:20260531T184419
CREATED:20231016T110452Z
LAST-MODIFIED:20231128T125246Z
UID:6696-1701790200-1701795600@crc326gaus.de
SUMMARY:Theta functions for the projective plane relative a smooth cubic
DESCRIPTION:Seminar on Arithmetic Geometry \nHelge Ruddat (University of Stavanger) \nGross-Hacking-Siebert generalized the classical Jacobi theta function from abelian varieties to more general log Calabi-Yau manifolds. Landau-Ginzburg superpotentials in mathematical physics give particular examples of such theta functions. Zaslow\, Gräfnitz and I compute the Landau-Ginzburg superpotential of the mirror symmetry dual of P^2 relative a smooth elliptic curve. This infinite power series is tropically defined and can be identified with a generating function for 2-contact point rational Gromov-Witten invariants of (X\,E). We found that this series also equals the open mirror map for outer Aganagic-Vafa branes in the canonical bundle K_X\, so it is closely related to a solution to a Lerche-Mayr system of two differential equations and it is also a generating function of holomorphic disk counts. The fundamental structure used to study theta functions is the wall structure. I am going to explain the background and usefulness of this recent technology. \nZoom (635 7328 0984\, Password: smallest six digit prime).
URL:https://crc326gaus.de/event/tba-85/
LOCATION:Darmstadt\, Room 244 and Zoom\, Schlossgartenstraße 7\, Darmstadt\, 64289
CATEGORIES:GAUS-Seminar
ORGANIZER;CN="Sabrina Pauli":MAILTO:pauli@mathematik.tu-darmstadt.de
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20231205T160000
DTEND;TZID=Europe/Berlin:20231205T170000
DTSTAMP:20260531T184419
CREATED:20231009T104848Z
LAST-MODIFIED:20231128T105630Z
UID:6411-1701792000-1701795600@crc326gaus.de
SUMMARY:Murmurations of holomorphic modular forms in the weight aspect
DESCRIPTION:International Seminar on Automorphic Forms \nMin Lee (University of Bristol) \nIn April 2022\, He\, Lee\, Oliver\, and Pozdnyakov made an interesting discovery using machine learning – a surprising correlation between the root numbers of elliptic curves and the coefficients of their L-functions. They coined this correlation ‘murmurations of elliptic curves.’ Naturally\, one might wonder whether we can identify a common thread of ‘murmurations’ in other families of L-functions. In this talk\, I will introduce a joint work with Jonathan Bober\, Andrew R. Booker and David Lowry-Duda\, demonstrating murmurations in holomorphic modular forms. \nhttps://tu-darmstadt.zoom.us/j/68048280736 \nThe password is the first Fourier coefficient of the modular j-function (as digits).
URL:https://crc326gaus.de/event/tba-67/
LOCATION:Zoom
CATEGORIES:GAUS-Seminar
ORGANIZER;CN="Claire Burrin":MAILTO:claire.burrin@math.uzh.ch
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20231206T160000
DTEND;TZID=Europe/Berlin:20231206T170000
DTSTAMP:20260531T184419
CREATED:20231120T080333Z
LAST-MODIFIED:20231127T102533Z
UID:7047-1701878400-1701882000@crc326gaus.de
SUMMARY:Global Smoothings of Toroidal Crossing Varieties
DESCRIPTION:Oberseminar Algebra und Geometrie \nHelge Ruddat (University of Stavanger) \nAs a natural generalization of normal crossing singularities\, I am going to define toroidal crossing singularities and toroidal crossing varieties and explain how to produce them in large quantities by subdividing lattice polytopes. I will then explain the statement of a global smoothing theorem proved jointly with Felten and Filip. The theorem follows the tradition of well-known theorems by Friedman\, Kawamata-Namikawa and Gross-Siebert. In order to apply a variant of the theorem to construct (conjecturally all) projective Fano manifolds with non-empty anticanonical divisor\, Corti and Petracci discovered the necessity to allow for particular singular log structures that are known by the inspiring name “admissible”‘. I will explain the beautiful classical geometric curve-in-surface geometry that underlies this notion and hint at why we believe that we can feed these singular log structures into the smoothing theorem in order to produce all 98 Fano threefolds with very ample anticanonical class by a single method.
URL:https://crc326gaus.de/event/tba-94/
LOCATION:Frankfurt\, Robert-Mayer-Str. 10\, Raum 711 groß
CATEGORIES:GAUS-Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20231212T160000
DTEND;TZID=Europe/Berlin:20231212T170000
DTSTAMP:20260531T184419
CREATED:20231009T105043Z
LAST-MODIFIED:20231204T084236Z
UID:6413-1702396800-1702400400@crc326gaus.de
SUMMARY:Resonances of Schottky surfaces
DESCRIPTION:International Seminar on Automorphic Forms \nAnke Pohl (University of Bremen) \nThe investigation of L^2-Laplace eigenvalues and eigenfunctions for hyperbolic surfaces of finite area is a classical and exciting topic at the intersection of number theory\, harmonic analysis and mathematical physics. In stark contrast\, for (geometrically finite) hyperbolic surfaces of infinite area\, the discrete L^2-spectrum is finite. A natural replacement are the resonances of the considered hyperbolic surface\, which are the poles of the meromorphically continued resolvent of the Laplacian. \nThese spectral entities also play an important role in number theory and various other fields\, and many fascinating results about them have already been found; the generalization of Selberg’s 3/16-theorem by Bourgain\, Gamburd and Sarnak is a well-known example. However\, an enormous amount of the properties of such resonances\, also some very elementary ones\, is still undiscovered. A few years ago\, by means of numerical experiments\, Borthwick noticed for some classes of Schottky surfaces (hyperbolic surfaces of infinite area without cusps and conical singularities) that their sets of resonances exhibit unexcepted and nice patterns\, which are not yet fully understood. \nAfter a brief survey of some parts of this field\, we will discuss an alternative numerical method\, combining tools from dynamics\, zeta functions\, transfer operators and thermodynamic formalism\, functional analysis and approximation theory. The emphasis of the presentation will be on motivation\, heuristics and pictures. This is joint work with Oscar Bandtlow\, Torben Schick and Alex Weisse. \nhttps://tu-darmstadt.zoom.us/j/68048280736 \nThe password is the first Fourier coefficient of the modular j-function (as digits).
URL:https://crc326gaus.de/event/tba-68/
LOCATION:Zoom
CATEGORIES:GAUS-Seminar
ORGANIZER;CN="Claire Burrin":MAILTO:claire.burrin@math.uzh.ch
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20231214T141500
DTEND;TZID=Europe/Berlin:20231214T151500
DTSTAMP:20260531T184419
CREATED:20231012T090245Z
LAST-MODIFIED:20231207T075847Z
UID:6652-1702563300-1702566900@crc326gaus.de
SUMMARY:Quadratic Atiyah-Bott Localisation
DESCRIPTION:Alessandro d’Angelo (Stockholm) \nAbstract: The Atiyah-Bott localisation theorem and the Graber-Pandharipande virtual localisation formula are standard tools for studying enumerative problems in the presence of a torus action. M. Levine proved similar results for Witt sheaf cohomology\, allowing us to retain quadratic information about the enumerative count. We will show how to extend the Atiyah-Bott localisation theorem to any SL-oriented motivic spectrum\, once the algebraic Hopf map is inverted. As an application\, we will also provide the appropriate virtual localisation formula for fundamental classes in this context. \nZoom Meeting-ID: 967 5163 9626 \nPasscode: last name of famous mathematician born in Königsberg (small letters)
URL:https://crc326gaus.de/event/tba-78/
LOCATION:Mainz\, Hilbertraum 05-432
CATEGORIES:GAUS-Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20231214T143000
DTEND;TZID=Europe/Berlin:20231214T153000
DTSTAMP:20260531T184419
CREATED:20231107T120412Z
LAST-MODIFIED:20231204T112155Z
UID:6926-1702564200-1702567800@crc326gaus.de
SUMMARY:Stationary Descendents and the Discriminant Modular Form
DESCRIPTION:TGiF-Seminar: Tropical geometry in Frankfurt (First meeting Winter Semester 2023/24) \nAdam Afandi (Universität Münster) \nAbstract: By using the Gromov-Witten/Hurwitz correspondence\, Okounkov and Pandharipande showed that certain generating functions of stationary descendent Gromov-Witten invariants of a smooth elliptic curve are quasimodular forms. In this talk\, I will discuss the various ways one can express the discriminant modular form in terms of these generating functions. The motivation behind this calculation is to provide a new perspective on tackling a longstanding conjecture of Lehmer from the middle of the 20th century; Lehmer posited that the Ramanujan tau function (i.e. the Fourier coefficients of the discriminant modular form) never vanishes. The connection with Gromov-Witten invariants allows one to translate Lehmer’s conjecture into a combinatorial problem involving characters of the symmetric group and shifted symmetric functions.
URL:https://crc326gaus.de/event/tba-92/
LOCATION:Frankfurt\, Robert-Mayer-Str. 10\, Raum 711 groß
CATEGORIES:GAUS-Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20231214T160000
DTEND;TZID=Europe/Berlin:20231214T170000
DTSTAMP:20260531T184419
CREATED:20231107T121051Z
LAST-MODIFIED:20231204T112026Z
UID:6928-1702569600-1702573200@crc326gaus.de
SUMMARY:Refined tropical curve counting with descendants
DESCRIPTION:TGiF-Seminar: Tropical geometry in Frankfurt (First meeting Winter Semester 2023/24) \nAjith Urundolil-Kumaran (University of Cambridge) \nAbstract: We introduce the enumerative geometry of curves in the algebraic torus (C*)^2. We show that a certain class of invariants associated with moduli spaces of curves in (C*)^2 can be calculated explicitly using a refined tropical correspondence theorem. If time permits we will explain how the proof relies on higher double ramification cycles and work of Buryak-Rossi on integrable systems on the moduli space of curves. This is joint work with Patrick Kennedy-Hunt and Qaasim Shafi. \n 
URL:https://crc326gaus.de/event/tba-93/
LOCATION:Frankfurt\, Robert-Mayer-Str. 10\, Raum 711 groß
CATEGORIES:GAUS-Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20231215T133000
DTEND;TZID=Europe/Berlin:20231215T150000
DTSTAMP:20260531T184419
CREATED:20231206T105109Z
LAST-MODIFIED:20231206T105410Z
UID:7399-1702647000-1702652400@crc326gaus.de
SUMMARY:Torsion in Griffiths Groups
DESCRIPTION:Theodosis Alexandrou (Universität Hannover) \nThe Griffiths group $Griff^{i}(X)$ of a smooth complex projective variety $X$ is the group of nullhomologous codimension$-i$ cycles on $X$ modulo algebraic equivalence. Recently Schreieder gave the first examples of smooth complex projective varieties $X$ for which the Griffiths group has infinite torsion. In his examples the infinitely many torsion classes are of order 2. In this talk we show that for any integer $n\geq 2$\, there is a smooth complex projective $5-$fold $X$ whose third Griffiths group contains infinitely many torsion elements of order $n$.
URL:https://crc326gaus.de/event/torsion-in-griffiths-groups/
LOCATION:Heidelberg\, Mathematikon\, SR A and Livestream
CATEGORIES:GAUS-Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20231215T153000
DTEND;TZID=Europe/Berlin:20231215T170000
DTSTAMP:20260531T184419
CREATED:20231016T110711Z
LAST-MODIFIED:20231205T130426Z
UID:6698-1702654200-1702659600@crc326gaus.de
SUMMARY:Motivic Linking
DESCRIPTION:Seminar on Arithmetic Geometry \nClémentine Lemarié—Rieusset (University of Burgundy) \nIn this talk I will present motivic linking\, a new application in algebraic geometry of motivic homotopy theory (specifically\, of quadratic intersection theory). Over a perfect field F\, motivic linking consists in the study of how two (nice) closed F-subschemes of a (nice) ambient F-scheme are linked (i.e. intertwined) and is a counterpart to linking in knot theory. More specifically\, I will present counterparts in algebraic geometry to the linking number of two oriented disjoint knots (the number of times one of the knots turns around the other knot). For the most part\, these counterparts take values in the Witt group of F or in the Grothendieck-Witt group of F\, rather than in the group of integers. There will be several examples\, including closed immersions between smooth models of motivic spheres and closed immersions between projective spaces. \nZoom (635 7328 0984\, Password: smallest six digit prime).
URL:https://crc326gaus.de/event/tba-86/
LOCATION:Darmstadt\, Room 401 and Zoom\, Schlossgartenstraße 7\, Darmstadt\, 64289\, Germany
CATEGORIES:GAUS-Seminar
ORGANIZER;CN="Sabrina Pauli":MAILTO:pauli@mathematik.tu-darmstadt.de
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20231222T153000
DTEND;TZID=Europe/Berlin:20231222T170000
DTSTAMP:20260531T184419
CREATED:20231016T110911Z
LAST-MODIFIED:20231215T072743Z
UID:6700-1703259000-1703264400@crc326gaus.de
SUMMARY:Deformations of $(G\,\mu)$-Displays
DESCRIPTION:Seminar on Arithmetic Geometry \nMohammad Hadi Hedayatzadeh (Institute for Research in Fundamental Sciences) \nIn this talk\, I will discuss a joint project with A. Partofard\, on prismatic displays with additional structures. I will start with a concise overview of the theory of displays developed by Th. Zink\, which serves as a generalization of Dieudonné theory. Displays play a crucial role in the study of Barsotti-Tate groups when the base is not a perfect field of positive characteristic. Zink has further expanded the theory by introducing windows over frames. In another direction\, in order to construct integral models of certain Shimura varieties that are not of Abelian type\, O. Bültel defined and studied displays with additional structures called $(G\,\mu)$-displays. \nIn this joint project with Partofard\, we define and study the stack of prismatic $(G\,\mu)$-displays over the quasi-syntomic site\, which is better adapted to the setting of pefectoid geometry and is closely related to the stack of $G$-torsors over the Fargues-Fontaine curve and local Shimura varieties. When $G$ is the general linear group\, our stack is the same as the stack of admissible prismatic $F$-crystals developed by Anschütz-LeBras\, which is equivalent to the stack of $p$-divisible groups. We also prove a Grothendieck-Messing style deformation result for these prismatic displays\, which\, for the general linear group\, answers a question of Anschütz-LeBras. \nZoom (635 7328 0984\, Password: smallest six digit prime).
URL:https://crc326gaus.de/event/tba-87/
LOCATION:Darmstadt\, Room 401 and Zoom\, Schlossgartenstraße 7\, Darmstadt\, 64289\, Germany
CATEGORIES:GAUS-Seminar
ORGANIZER;CN="Sabrina Pauli":MAILTO:pauli@mathematik.tu-darmstadt.de
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20240112T133000
DTEND;TZID=Europe/Berlin:20240112T150000
DTSTAMP:20260531T184419
CREATED:20240101T193202Z
LAST-MODIFIED:20240101T193202Z
UID:7526-1705066200-1705071600@crc326gaus.de
SUMMARY:Equivariant motives and actions of finite reductive groups
DESCRIPTION:Can Yaylali (Darmstadt/Paris) \nAbstract: A finite reductive group G^F is defined as the fixed points of a reductive group G/F_q under the q-Frobenius endomorphism. Their representations were studied by Deligne-Lusztig and Brokemper gave a description of the G^F-equivariant intersection ring of a point (the ring classifying G^F-invariant cycles). Focusing on the latter\, I will give an introduction to (rational) motives with group actions and how this is related to equivariant intersection theory. I will use this formalism to relate motives with G^F-action to equivariant motives on the associated flag variety. I will also explain how this relates to Brokemper’s computations on algebraic cycles. If time permits\, I will try to discuss the implications on l-adic cohomology and how this can be used in the future to study motivic representation theory of G^F following Deligne-Lusztig.
URL:https://crc326gaus.de/event/equivariant-motives-and-actions-of-finite-reductive-groups/
LOCATION:Heidelberg\, Mathematikon\, SR A and Livestream
CATEGORIES:GAUS-Seminar
ORGANIZER;CN="Christian Dahlhausen":MAILTO:cdahlhausen@mathi.uni-heidelberg.de
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20240116T160000
DTEND;TZID=Europe/Berlin:20240116T170000
DTSTAMP:20260531T184419
CREATED:20231009T105238Z
LAST-MODIFIED:20231221T093008Z
UID:6415-1705420800-1705424400@crc326gaus.de
SUMMARY:Automorphism group of Cartan modular curves
DESCRIPTION:International Seminar on Automorphic Forms \nPietro Mercuri (University of Rome – La Sapienza) \nWe consider the modular curves associated to a Cartan subgroup of GL(2\,Z/nZ) or to a particular class of subgroups of GL(2\,Z/nZ) containing the Cartan subgroup as a normal subgroup. We describe the automorphism group of these curves when the level is large enough. If time permits\, we give a sketch of the proof. \nhttps://tu-darmstadt.zoom.us/j/68048280736 \nThe password is the first Fourier coefficient of the modular j-function (as digits).
URL:https://crc326gaus.de/event/tba-69/
LOCATION:Darmstadt\, Room 401 and Zoom\, Schlossgartenstraße 7\, Darmstadt\, 64289\, Germany
CATEGORIES:GAUS-Seminar
ORGANIZER;CN="Claire Burrin":MAILTO:claire.burrin@math.uzh.ch
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20240119T140000
DTEND;TZID=Europe/Berlin:20240119T180000
DTSTAMP:20260531T184419
CREATED:20231123T090322Z
LAST-MODIFIED:20231123T090429Z
UID:7232-1705672800-1705687200@crc326gaus.de
SUMMARY:Conformal Field Theory
DESCRIPTION:14:00-15:00: Britta Spät (University of Wuppertal): On the McKay Conjecture \n15:15-16:15: Ida Zadeh (Johannes Gutenberg University Mainz): Mathieu Moonshine and T4/Z3 sigma-models \n17:00-18:00: David Reutter (University of Hamburg): A braided tensor 2-category from link homology
URL:https://crc326gaus.de/event/conformal-field-theory/
LOCATION:Darmstadt\, Room S214/24
CATEGORIES:GAUS-Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20240119T153000
DTEND;TZID=Europe/Berlin:20240119T170000
DTSTAMP:20260531T184419
CREATED:20231016T111231Z
LAST-MODIFIED:20240112T073106Z
UID:6704-1705678200-1705683600@crc326gaus.de
SUMMARY:Enumerating motivic nearby cycles
DESCRIPTION:Seminar on Arithmetic Geometry \nRan Azouri (Sorbonne Paris North University) \nA^1 homotopy theory provides tools to refine geometric invariants on integers to quadratic forms. A key such invariant is the quadratic Euler characteristic; Ayoub’s motivic nearby cycles provide a tool to study singularities in the world of A^1 homotopy.\nIn the talk I will explain how to compute the quadratic Euler characteristic on the motivic nearby cycles spectrum around certain singularities\, using an explicit semistable reduction construction. This\, together with a work of Levine\, Pepin Lehalleur and Srinivas\, adds up to a quadratic conductor formula on schemes with semi-quasihomogeneous singularities\, refining formulas of Milnor and Deligne.\nLater I will describe how\, in a work in progress with Emil Jacobsen\, we use a similar semistable reduction argument to compute the motivic monodromy on nearby cycles\, generalising to motives the Picard-Lefschetz formula of Deligne and Katz. \nZoom (635 7328 0984\, Password: smallest six digit prime).
URL:https://crc326gaus.de/event/tba-89/
LOCATION:Darmstadt\, Room 401 and Zoom\, Schlossgartenstraße 7\, Darmstadt\, 64289\, Germany
CATEGORIES:GAUS-Seminar
ORGANIZER;CN="Sabrina Pauli":MAILTO:pauli@mathematik.tu-darmstadt.de
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20240123T090000
DTEND;TZID=Europe/Berlin:20240123T100000
DTSTAMP:20260531T184419
CREATED:20231009T105405Z
LAST-MODIFIED:20240109T101527Z
UID:6417-1706000400-1706004000@crc326gaus.de
SUMMARY:The BZSV duality and the relative Langlands program
DESCRIPTION:International Seminar on Automorphic Forms \nWee Teck Gan (National University of Singapore) \nI will discuss a duality of Hamiltonian group varieties proposed in a recent preprint of Ben-Zvi\, Sakellaridis and Venkatesh\, which gives a new paradigm for the relative Langlands program.\nI will then discuss a joint work with Bryan Wang on instances of this duality for certain Hamiltonian varieties which quantize to generalized Whittaker models. \nYou can join the Zoom meeting at https://tu-darmstadt.zoom.us/j/68048280736 \nThe password is the first Fourier coefficient of the modular j-function (as digits).
URL:https://crc326gaus.de/event/tba-70/
LOCATION:Zoom
CATEGORIES:GAUS-Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20240123T140000
DTEND;TZID=Europe/Berlin:20240123T150000
DTSTAMP:20260531T184419
CREATED:20231220T150741Z
LAST-MODIFIED:20231220T151059Z
UID:7510-1706018400-1706022000@crc326gaus.de
SUMMARY:Étale cohomology of the moduli stack of rank 2 vector bundles on the Fargues-Fontaine curve
DESCRIPTION:Seminar: Non-archimedean geometry \nRuth Wild (Universität Bonn) \nAbstract: Motivated by classical calculations\, we consider the problem of calculating the etale cohomology of the moduli stack Bun<sub>2</sub> of rank 2 vector bundles on the Fargues-Fontaine curve\, as introduced by Fargues and Scholze in their geometrization of the Local Langlands correspondence. We achive this by analyzing a stratafication of this stack and the simple cohomological behavior of the different strata. Along the way\, we prove the description of the dualizing sheaf on Bun<sub>2</sub>.
URL:https://crc326gaus.de/event/etale-cohomology-of-the-moduli-stack-of-rank-2-vector-bundles-on-the-fargues-fontaine-curve/
LOCATION:Frankfurt\, Rober-Mayer-Str. 10\, Raum 711 klein
CATEGORIES:GAUS-Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20240125T170000
DTEND;TZID=Europe/Berlin:20240125T180000
DTSTAMP:20260531T184419
CREATED:20231012T090458Z
LAST-MODIFIED:20240514T072156Z
UID:6654-1706202000-1706205600@crc326gaus.de
SUMMARY:CRC-Colloquium
DESCRIPTION:15:30 Uhr Ben Heuer (Universität Frankfurt): p-adic non-abelian Hodge theory for non-p-adic mathematicians\n16:30 Coffee and Cake\n17:00 Uhr Jan Bruinier (TU Darmstadt): Theta functions in geometry and arithmetic\n18:30 Uhr: Dinner \nAbstract B. Heuer:\nIn p-adic non-abelian Hodge theory\, we study p-adic representations of fundamental groups of projective varieties. This talk will give an introduction to this subject without assuming any background in p-adic geometry. Based on examples\, I will explain the “p-adic Simpson correspondence”\, with an emphasis on the relation to complex geometry. I will discuss recent advances\, the main open questions in the area\, and potential applications to complex geometry. \nAbstract J. Brunier:\nWe explain how theta functions can be used to study positive definite quadratic forms and their representation numbers. For indefinite quadratic forms\, Kudla and Millson showed that there are analogous theta functions relating the geometry of special cycles on locally symmetric spaces to modular forms. Conjectures of Kudla predict similar results for arithmetic special cycles in Arakelov Chow groups on integral models of orthogonal Shimura varieties. We will also report on some recent results in this context. \nZoom Meeting-ID: 967 5163 9626 \nPasscode: last name of famous mathematician born in Königsberg (small letters)
URL:https://crc326gaus.de/event/tba-79/
LOCATION:Mainz\, Raum 05-426
CATEGORIES:GAUS-Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20240126T143000
DTEND;TZID=Europe/Berlin:20240126T153000
DTSTAMP:20260531T184419
CREATED:20240108T113933Z
LAST-MODIFIED:20240123T144642Z
UID:7541-1706279400-1706283000@crc326gaus.de
SUMMARY:Hard Lefschetz theorem and Hodge-Riemann relations for convex valuations
DESCRIPTION:TGiF-Seminar: Tropical geometry in Frankfurt (Second meeting Winter Semester 2023/24) \nCancelled: postponed to February 02 \nAndreas Bernig (Goethe-Universität Frankfurt) \nAbstract: The hard Lefschetz theorem and the Hodge-Riemann relations have their origin in the cohomology theory of compact Kähler manifolds. In recent years it has become clear that similar results hold in many different settings\, in particular in algebraic geometry and combinatorics (work by Adiprasito\, Huh and others). In a recent joint work with Jan Kotrbatý and Thomas Wannerer\, we prove the hard Lefschetz theorem and Hodge-Riemann relations for valuations on convex bodies. These results can be translated into an array of quadratic inequalities for mixed volumes of smooth convex bodies\, giving a smooth analogue of the quadratic inequalities in McMullen’s polytope algebra. Surprinsingly\, these inequalities fail for general convex bodies. Our proof uses elliptic operators and perturbation theory of unbounded operators.
URL:https://crc326gaus.de/event/hard-lefschetz-theorem-and-hodge-riemann-relations-for-convex-valuations/
LOCATION:Frankfurt\, Robert-Mayer-Str. 10\, Raum 711 groß
CATEGORIES:GAUS-Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20240126T153000
DTEND;TZID=Europe/Berlin:20240126T170000
DTSTAMP:20260531T184419
CREATED:20231016T111405Z
LAST-MODIFIED:20240117T141441Z
UID:6706-1706283000-1706288400@crc326gaus.de
SUMMARY:Doing geometry by counting points
DESCRIPTION:Seminar on Arithmetic Geometry \nPaul Ziegler (TU Darmstadt) \nFor a family of polynomials in several variables with integral coefficients\, the Weil conjectures give a surprising relationship between the geometry of the complex-valued roots of these polynomials and the number of roots of these polynomials “modulo p”. I will give an introduction to this circle of results and an application motivated by the concept of mirror symmetry from physics. \nZoom (635 7328 0984\, Password: smallest six digit prime).
URL:https://crc326gaus.de/event/tba-90/
LOCATION:Darmstadt\, Room 244 and Zoom\, Schlossgartenstraße 7\, Darmstadt\, 64289
CATEGORIES:GAUS-Seminar
ORGANIZER;CN="Sabrina Pauli":MAILTO:pauli@mathematik.tu-darmstadt.de
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20240126T160000
DTEND;TZID=Europe/Berlin:20240126T170000
DTSTAMP:20260531T184419
CREATED:20231221T132521Z
LAST-MODIFIED:20240123T144823Z
UID:7519-1706284800-1706288400@crc326gaus.de
SUMMARY:Category of matroids with coefficients
DESCRIPTION:TGiF-Seminar: Tropical geometry in Frankfurt (Second meeting Winter Semester 2023/24) \nCancelled: postponed to February 02 \nManoel Zanoelo Jarra (Universität Groningen) \nAbstract: Matroids are combinatorial abstractions of the concept of independence in linear algebra. There is a way back: when representing a matroid over a field we get a linear subspace. Another algebraic object for which we can represent matroids is the semifield of tropical numbers\, which gives us valuated matroids. In this talk we introduce Baker-Bowler’s theory of matroids with coefficients\, which recovers both classical and valuated matroids\, as well linear subspaces\, and we show how to give a categorical treatment to these objects that respects matroidal constructions\, as minors and duality. This is a joint work with Oliver Lorscheid and Eduardo Vital.
URL:https://crc326gaus.de/event/tba-95/
LOCATION:Frankfurt\, Robert-Mayer-Str. 10\, Raum 711 groß
CATEGORIES:GAUS-Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20240130T160000
DTEND;TZID=Europe/Berlin:20240130T170000
DTSTAMP:20260531T184419
CREATED:20231009T105559Z
LAST-MODIFIED:20240123T160326Z
UID:6420-1706630400-1706634000@crc326gaus.de
SUMMARY:Six-dimensional sphere packing and linear programming
DESCRIPTION:International Seminar on Automorphic Forms \nMatthew de Courcy-Ireland (Stockholm University) \nThis talk is based on joint work with Maria Dostert and Maryna Viazovska. We prove that the Cohn–Elkies linear programming bound is not sharp for sphere packing in dimension 6. This is in contrast to Viazovska’s sharp bound in dimension 8\, even though it is believed that closely related lattices achieve the optimal densities in both dimensions. The proof uses modular forms to construct feasible points in a dual program\, generalizing a construction of Cohn and Triantafillou to the case of odd weight and non-trivial Dirichlet character. Non-sharpness of linear programming is demonstrated by comparing this dual bound to a stronger upper bound obtained from semidefinite programming by Cohn\, de Laat\, and Salmon. Our construction has vanishing Fourier coefficients along an arithmetic progression\, which can be explained using skew self-adjointness of Hecke operators. \nYou can join the Zoom meeting at https://tu-darmstadt.zoom.us/j/68048280736 \nThe password is the first Fourier coefficient of the modular j-function (as digits).
URL:https://crc326gaus.de/event/tba-71/
LOCATION:Zoom
CATEGORIES:GAUS-Seminar
ORGANIZER;CN="Claire Burrin":MAILTO:claire.burrin@math.uzh.ch
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20240201T141500
DTEND;TZID=Europe/Berlin:20240201T151500
DTSTAMP:20260531T184419
CREATED:20231012T090600Z
LAST-MODIFIED:20240125T100727Z
UID:6656-1706796900-1706800500@crc326gaus.de
SUMMARY:On the motivic fundamental group
DESCRIPTION:Emil Jacobsen (Stockholm) \nAbstract: I will introduce the motivic fundamental group of a smooth variety\, and explain its relation to the usual fundamental group. The main result can also be phrased as follows: local systems of geometric origin are stable under extension in the category of local systems. I will also present a motivic version of a classical theorem of Hain\, on Malcev completions of monodromy representations. At the end\, I’ll explain some of the group/representation theoretic tools that go into these result. \nZoom Meeting-ID: 967 5163 9626 \nPasscode: last name of famous mathematician born in Königsberg (small letters)
URL:https://crc326gaus.de/event/tba-80/
LOCATION:Mainz\, Hilbertraum 05-432
CATEGORIES:GAUS-Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20240202T133000
DTEND;TZID=Europe/Berlin:20240202T150000
DTSTAMP:20260531T184419
CREATED:20240126T120455Z
LAST-MODIFIED:20240126T120455Z
UID:7637-1706880600-1706886000@crc326gaus.de
SUMMARY:On Voevodsky's reconstruction theorem
DESCRIPTION:Sebastian Wolf (Universität Regensburg) \nIn 1990\, Voevodsky proved a conjecture of Grothendieck\, that morphisms of normal schemes of finite type over the rational numbers can be reconstructed from the induced morphism of étale topoi. The goal of this talk is to give an outline of Voevodsky’s proof and explain how to extend it to certain sufficiently nice singular schemes. If time permits\, we will also see what one has to modify to make it work in positive characteristic. This is joint work with Peter Haine.
URL:https://crc326gaus.de/event/on-voevodskys-reconstruction-theorem/
LOCATION:Heidelberg\, Mathematikon\, SR A and Livestream
CATEGORIES:GAUS-Seminar
ORGANIZER;CN="Tim Holzschuh":MAILTO:tholzschuh@mathi.uni-heidelberg.de
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20240202T143000
DTEND;TZID=Europe/Berlin:20240202T153000
DTSTAMP:20260531T184419
CREATED:20240123T143810Z
LAST-MODIFIED:20240123T143810Z
UID:7614-1706884200-1706887800@crc326gaus.de
SUMMARY:Hard Lefschetz theorem and Hodge-Riemann relations for convex valuations
DESCRIPTION:TGiF-Seminar: Tropical geometry in Frankfurt (Second meeting Winter Semester 2023/24) \nAndreas Bernig (Goethe-Universität Frankfurt) \nAbstract: The hard Lefschetz theorem and the Hodge-Riemann relations have their origin in the cohomology theory of compact Kähler manifolds. In recent years it has become clear that similar results hold in many different settings\, in particular in algebraic geometry and combinatorics (work by Adiprasito\, Huh and others). In a recent joint work with Jan Kotrbatý and Thomas Wannerer\, we prove the hard Lefschetz theorem and Hodge-Riemann relations for valuations on convex bodies. These results can be translated into an array of quadratic inequalities for mixed volumes of smooth convex bodies\, giving a smooth analogue of the quadratic inequalities in McMullen’s polytope algebra. Surprinsingly\, these inequalities fail for general convex bodies. Our proof uses elliptic operators and perturbation theory of unbounded operators.
URL:https://crc326gaus.de/event/hard-lefschetz-theorem-and-hodge-riemann-relations-for-convex-valuations-2/
LOCATION:Frankfurt\, Robert-Mayer-Str. 10\, Raum 711 groß
CATEGORIES:GAUS-Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20240202T153000
DTEND;TZID=Europe/Berlin:20240202T170000
DTSTAMP:20260531T184419
CREATED:20231016T111637Z
LAST-MODIFIED:20240123T160047Z
UID:6708-1706887800-1706893200@crc326gaus.de
SUMMARY:Gluing sheaves along Harder-Narasimhan strata of Bun_2.
DESCRIPTION:Seminar on Arithmetic Geometry \nJonathan Miles (University of Frankfurt) \nWe explain how to glue sheaves on the moduli stack of G-bundles on the Fargues-Fontaine curve. In the case of prime-to-p torsion coefficients\, the category D_ét(Bun_G) can be thought of as an approximation of the automorphic data appearing in the geometrization of the local Langlands correspondence due to Fargues-Scholze. The stratification of Bun_G arising from the Harder-Narasimhan slope formalism on G-isocrystals yields a semi-orthogonal decomposition of D_ét(Bun_G) into the derived categories of smooth representations of inner forms of Levi subgroups of G. Between such categories there is a (partial) six functor formalism that can be used to compute how sheaves arising on a quasi-compact open substack interact with sheaves on higher strata via nearby cycles functors\, which can be interpreted as a derived analogue of Jacquet restriction functors for parabolic subgroups of G (up to inner twisting). We eventually restrict to G=GL_2 and to sufficiently nice coefficients (notably this includes an algebraic closure of F_\ell and Z/\ell^n Z for almost all \ell prime to p)\, and we will explain how these computations fundamentally reduce to the étale cohomology of p-adic analogues of locally symmetric spaces\, such as the Bruhat-Tits building and moduli spaces of mixed p-adic Hodge structures. \nZoom (635 7328 0984\, Password: smallest six digit prime).
URL:https://crc326gaus.de/event/tba-91/
LOCATION:Darmstadt\, Room 401 and Zoom\, Schlossgartenstraße 7\, Darmstadt\, 64289\, Germany
CATEGORIES:GAUS-Seminar
ORGANIZER;CN="Sabrina Pauli":MAILTO:pauli@mathematik.tu-darmstadt.de
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20240202T160000
DTEND;TZID=Europe/Berlin:20240202T170000
DTSTAMP:20260531T184419
CREATED:20240123T143136Z
LAST-MODIFIED:20240123T143136Z
UID:7615-1706889600-1706893200@crc326gaus.de
SUMMARY:Category of matroids with coefficients
DESCRIPTION:TGiF-Seminar: Tropical geometry in Frankfurt (Second meeting Winter Semester 2023/24) \nManoel Zanoelo Jarra (Universität Groningen) \nAbstract: Matroids are combinatorial abstractions of the concept of independence in linear algebra. There is a way back: when representing a matroid over a field we get a linear subspace. Another algebraic object for which we can represent matroids is the semifield of tropical numbers\, which gives us valuated matroids. In this talk we introduce Baker-Bowler’s theory of matroids with coefficients\, which recovers both classical and valuated matroids\, as well linear subspaces\, and we show how to give a categorical treatment to these objects that respects matroidal constructions\, as minors and duality. This is a joint work with Oliver Lorscheid and Eduardo Vital.
URL:https://crc326gaus.de/event/category-of-matroids-with-coefficients/
LOCATION:Frankfurt\, Robert-Mayer-Str. 10\, Raum 711 groß
CATEGORIES:GAUS-Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20240206T160000
DTEND;TZID=Europe/Berlin:20240206T170000
DTSTAMP:20260531T184419
CREATED:20231009T105725Z
LAST-MODIFIED:20240130T085731Z
UID:6422-1707235200-1707238800@crc326gaus.de
SUMMARY:Evaluating the wild Brauer group
DESCRIPTION:International Seminar on Automorphic Forms \nRachel Newton (King’s College London) \nThe local-global approach to the study of rational points on varieties over number fields begins by embedding the set of rational points on a variety X into the set of its adelic points. The Brauer–Manin pairing cuts out a subset of the adelic points\, called the Brauer–Manin set\, that contains the rational points. If the set of adelic points is non-empty but the Brauer–Manin set is empty then we say there’s a Brauer–Manin obstruction to the existence of rational points on X. Computing the Brauer–Manin pairing involves evaluating elements of the Brauer group of X at local points. If an element of the Brauer group has order coprime to p\, then its evaluation at a p-adic point factors via reduction of the point modulo p. For p-torsion elements this is no longer the case: in order to compute the evaluation map one must know the point to a higher p-adic precision. Classifying Brauer group elements according to the precision required to evaluate them at p-adic points gives a filtration which we describe using work of Bloch and Kato. Applications of our work include addressing Swinnerton-Dyer’s question about which places can play a role in the Brauer–Manin obstruction. This is joint work with Martin Bright. \nYou can join the Zoom meeting at https://tu-darmstadt.zoom.us/j/68048280736 \nThe password is the first Fourier coefficient of the modular j-function (as digits).
URL:https://crc326gaus.de/event/tba-72/
LOCATION:Zoom
CATEGORIES:GAUS-Seminar
ORGANIZER;CN="Claire Burrin":MAILTO:claire.burrin@math.uzh.ch
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20240209T140000
DTEND;TZID=Europe/Berlin:20240209T153000
DTSTAMP:20260531T184419
CREATED:20231016T111058Z
LAST-MODIFIED:20240202T135000Z
UID:6702-1707487200-1707492600@crc326gaus.de
SUMMARY:Motivic tt-geometry
DESCRIPTION:Seminar on Arithmetic Geometry \nMartin Gallauer (University of Warwick) \nCommutative rings are profitably studied from a geometric point of view\, giving rise to the field of algebraic geometry. “Categorified commutative rings” (e.g. tt-categories) can similarly be studied geometrically\, leading to a field called tt-geometry. I will introduce these ideas and focus on recent progress regarding tt-categories arising in the motivic theory. (Based on joint work with Paul Balmer). \nZoom (635 7328 0984\, Password: smallest six digit prime).
URL:https://crc326gaus.de/event/tba-88/
LOCATION:Zoom
CATEGORIES:GAUS-Seminar
ORGANIZER;CN="Sabrina Pauli":MAILTO:pauli@mathematik.tu-darmstadt.de
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20240411T160000
DTEND;TZID=Europe/Berlin:20240411T170000
DTSTAMP:20260531T184419
CREATED:20240311T180923Z
LAST-MODIFIED:20240404T083751Z
UID:7886-1712851200-1712854800@crc326gaus.de
SUMMARY:The Two Lives of the Grassmannian
DESCRIPTION:Oberseminar Algebra und Geometrie \nBernd Sturmfels (MPI-MiS Leipzig) \nAbstract: \nThe Grassmannian parametrizes linear subspaces of a real vector space.\nIt is both a projective variety (via Plücker coordinates) and an affine\nvariety (via orthogonal projections). We examine these two representations\,\nthrough the lenses of linear algebra\, commutative algebra\, and statistics.
URL:https://crc326gaus.de/event/bernd-sturmfels-mpi-mis-the-two-lives-of-the-grassmannian/
LOCATION:Frankfurt\, Robert-Mayer-Str. 10\, Raum 711 groß
CATEGORIES:GAUS-Seminar
END:VEVENT
END:VCALENDAR