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BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20260512T123000
DTEND;TZID=Europe/Berlin:20260512T133000
DTSTAMP:20260619T213029
CREATED:20260529T091040Z
LAST-MODIFIED:20260529T091239Z
UID:13457-1778589000-1778592600@crc326gaus.de
SUMMARY:AGTZ-Kolloquium
DESCRIPTION:Carl Mautner (University of California\, Riverside\, USA) \nHilbert schemes\, perverse sheaves and a new Schur algebra \nThe Schur algebra is a finite-dimensional algebra that connects the representation theory of the symmetric and general linear groups. In joint work with Tom Braden\, we give an algebraic description of the category of perverse sheaves with coefficients in a field of characteristic p on S^n(C^2)\, the n-fold symmetric product of the plane\, in terms of a new\, enhanced version of the Schur algebra. This work is motivated by a geometric description of the standard Schur algebra and the theory of symplectic duality.
URL:https://crc326gaus.de/event/agtz-kolloquium-2/
LOCATION:Mainz\, Hilbertraum (05-432)
CATEGORIES:GAUS-Seminar
ORGANIZER;CN="Georg Tamme":MAILTO:georg.tamme@uni-mainz.de
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20260518T160000
DTEND;TZID=Europe/Berlin:20260518T180000
DTSTAMP:20260619T213029
CREATED:20260413T115012Z
LAST-MODIFIED:20260427T082319Z
UID:13049-1779120000-1779127200@crc326gaus.de
SUMMARY:Oberseminar Algebra und Geometrie
DESCRIPTION:Michael Temkin (MPI Bonn): Wild Hurwitz spaces and level structures \n\nAbstract: Hurwitz moduli spaces of covers of curves of degree d are classical and well studied objects if one assumes that d! is invertible and hence no wild ramification phenomena occur. There were very few attempts to study the wild case. In the most important one Abramovich and Oort started with the classical space H_{2\,1\,0\,4} of double covers of P^1 ramified at four points and (following an idea of Kontsevich and Pandariphande) described its schematic closure H in the space of stable maps over Z. The result over F_2 was both strange and informative\, but lacked a modular interpretation. \nIn the first part of my talk I will describe the example of Abramovich-Oort and then tell about a work in progress of Hippold\, where a (logarithmic) modular version of compactified Hurwitz space of degree p is constructed when only (p-1)! is invertible. In particular\, this conceptually explains phenomena observed by Abramovich-Oort. In the second part I will describe another outcome of the same ideas. It was observed by Abramovich-Oort that H is the blowing up of the modular curve X(2). This is not a coincidence\, and the same ideas can be used to refine the wild level structures of Drinfeld and construct modular interpretation of the minimal modifications of the curves X(p^n) which separate ordinary branches at any supersingular point. This is a very recent work in progress and the precise description of the obtained spaces is still to be found.
URL:https://crc326gaus.de/event/oberseminar-algebra-und-geometrie-6/
LOCATION:Frankfurt\, Robert-Mayer-Str. 6-8\, Raum 309
CATEGORIES:GAUS-Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20260521T141500
DTEND;TZID=Europe/Berlin:20260521T151500
DTSTAMP:20260619T213029
CREATED:20260529T091515Z
LAST-MODIFIED:20260529T091515Z
UID:13461-1779372900-1779376500@crc326gaus.de
SUMMARY:AGTZ Kolloquium
DESCRIPTION:Marc Hoyois (Uni Regensburg) \nPoincaré localizing invariants of schemes \nIn joint work with Markus Land\, we investigate motivic properties of Poincaré localizing invariants of schemes\, like Grothendieck-Witt theory\, and we establish that they satisfy a projective bundle formula and descent for the Nisnevich topology. This implies that the motivic sphere spectrum over (almost) any local ring R admits a faithful action of the Grothendieck-Witt group of nondegenerate symmetric bilinear forms over R.
URL:https://crc326gaus.de/event/agtz-kolloquium-3/
LOCATION:Mainz\, Hilbertraum (05-432)
CATEGORIES:GAUS-Seminar
ORGANIZER;CN="Georg Tamme":MAILTO:georg.tamme@uni-mainz.de
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20260522T133000
DTEND;TZID=Europe/Berlin:20260522T143000
DTSTAMP:20260619T213029
CREATED:20260505T075121Z
LAST-MODIFIED:20260505T075121Z
UID:13346-1779456600-1779460200@crc326gaus.de
SUMMARY:Construction of logarithmic cohomology theories
DESCRIPTION:Doosung Park (Wuppertal) \nIn this talk\, I will explain a functor extending cohomology theories from schemes to log schemes. Using this functor\, we can obtain the log cyclotomic trace\, and we can represent K-theory in the logarithmic motivic homotopy category. I will also explain an application to the p-adic deformation problem for the K-theory of semistable schemes.
URL:https://crc326gaus.de/event/construction-of-logarithmic-cohomology-theories/
LOCATION:Heidelberg\, Mathematikon\, SR A and Livestream
CATEGORIES:GAUS-Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20260522T140000
DTEND;TZID=Europe/Berlin:20260522T160000
DTSTAMP:20260619T213029
CREATED:20260511T122419Z
LAST-MODIFIED:20260511T122419Z
UID:13378-1779458400-1779465600@crc326gaus.de
SUMMARY:Toward the noncommutative minimal model program
DESCRIPTION:The aim of the talk is to introduce the noncommutative minimal model program (ncMMP) proposed by Halpern-Leistner and inspired by some works of Dubrovin and Kontsevich. For a given projective variety X\, the classical minimal model program asks if there is a variety Y that is birational to X but has simpler geometry\, such Y is called a minimal model of X. In the noncommutative context\, we consider the derived category D(X) of coherent sheaves on X\, and we ask if we can decompose it canonically. The biggest factor of the decomposition is then a minimal model for D(X). In order to find such a decomposition Halpern-Leistner proposes to use the quantum cohomology of X.\nWe will discuss some examples where Halpern-Leistner’s proposal is satisfied: Grassmannians\, quadrics\, and cubics in dimensions 3 and 4.
URL:https://crc326gaus.de/event/toward-the-noncommutative-minimal-model-program/
LOCATION:Heidelberg\, MATHEMATIKON\, SR 007\, Im Neuenheimer Feld 205\, Heidelberg\, 69120\, Germany
CATEGORIES:GAUS-Seminar
ORGANIZER;CN="Georg Bernhard Oberdieck":MAILTO:georgo@uni-heidelberg.de
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20260522T153000
DTEND;TZID=Europe/Berlin:20260522T170000
DTSTAMP:20260619T213029
CREATED:20260319T100054Z
LAST-MODIFIED:20260518T072739Z
UID:12873-1779463800-1779469200@crc326gaus.de
SUMMARY:Seminar on Arithmetic Geometry
DESCRIPTION:Lucien Hennecart (CNRS): The BPS sheaf for preprojective algebras and moduli of Higgs bundles \nIn the first part of the talk\, I will introduce the BPS sheaf associated with the preprojective algebra of a quiver. This is a perverse sheaf on the moduli space of representations\, endowed with a Lie algebra structure\, which encodes the Kac polynomials of the quiver. Its structure is described in terms of generators and relations in joint work with Davison and Schlegel Mejia. This description is formulated in terms of a generalized Kac–Moody algebra. \nIn the second part\, I will explain how this description makes it possible to determine the supports and local systems of the direct summands of the BPS sheaf. This description involves the geometry of hypertoric varieties in general\, and can in certain cases be simplified. Applying these results to the Hitchin fibration\, one recovers results due to de Cataldo\, Heinloth\, Migliorini\, and also Mauri\, concerning the effective decomposition theorem for the Hitchin morphism involving Ngo strings. This is all based on various discussions with Ben Davison. \nZoom (635 7328 0984\, Kenncode: kleinste sechsstellige Primzahl)
URL:https://crc326gaus.de/event/seminar-on-arithmetic-geometry-32/
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:20260527T160000
DTEND;TZID=Europe/Berlin:20260527T180000
DTSTAMP:20260619T213029
CREATED:20260512T073341Z
LAST-MODIFIED:20260513T120213Z
UID:13387-1779897600-1779904800@crc326gaus.de
SUMMARY:Oberseminar Algebra und Geometrie
DESCRIPTION:Konstantinos Kartas (Universität Münster): Taming perfectoid algebras \nAbstract: The almost purity theorem is a foundational result in perfectoid geometry which\, as the name suggests\, holds only in an “almost” sense. We aim to identify a class of rings for which the theorem holds in a genuine (non-almost) form. Joint work in progress with Franziska Jahnke. \n  \n 
URL:https://crc326gaus.de/event/oberseminar-algebra-und-geometrie-8/
LOCATION:Frankfurt\, Robert-Mayer-Str. 6-8\, Raum 309
CATEGORIES:GAUS-Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20260528T141500
DTEND;TZID=Europe/Berlin:20260528T151500
DTSTAMP:20260619T213029
CREATED:20260525T204255Z
LAST-MODIFIED:20260525T204255Z
UID:13441-1779977700-1779981300@crc326gaus.de
SUMMARY:Kolloquium Geometrie und Arithmetik
DESCRIPTION:Niklas Kipp (Paris-Saclay): A solid Syntomification \nAbstract: We will learn a strategy to obtain a well behaved six-functor formalism for Syntomic cohomology of p-adic formal schemes as defined by Bhatt-Morrow-Scholze. Here well behaved mainly refers to this six-functor formalism generalising Poincaré duality (which was proven by Longke Tang in the smooth and proper case) to smooth morphisms using a version of compactly supported syntomic cohomology. Concretely\, we will recall some aspects of the stacky approach to Prismatic/Syntomic cohomology (following Bhatt-Lurie and Drinfeld) as well as some aspects of the theory of (Solid) analytic stacks (following Clausen-Scholze). \n  \n 
URL:https://crc326gaus.de/event/kolloquium-geometrie-und-arithmetik/
LOCATION:Mainz\, Hilbertraum (05-432)
CATEGORIES:GAUS-Seminar
ORGANIZER;CN="Georg Tamme":MAILTO:georg.tamme@uni-mainz.de
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20260528T141500
DTEND;TZID=Europe/Berlin:20260528T151500
DTSTAMP:20260619T213029
CREATED:20260529T091856Z
LAST-MODIFIED:20260529T091856Z
UID:13464-1779977700-1779981300@crc326gaus.de
SUMMARY:AGTZ Kolloquium
DESCRIPTION:Niklas Kipp (Paris-Sanclay) \nA solid Syntomification \nWe will learn a strategy to obtain a well behaved six-functor formalism for Syntomic cohomology of p-adic formal schemes as defined by Bhatt-Morrow-Scholze. Here well behaved mainly refers to this six-functor formalism generalising Poincaré duality (which was proven by Longke Tang in the smooth and proper case) to smooth morphisms using a version of compactly supported syntomic cohomology. Concretely\, we will recall some aspects of the stacky approach to Prismatic/Syntomic cohomology (following Bhatt-Lurie and Drinfeld) as well as some aspects of the theory of (Solid) analytic stacks (following Clausen-Scholze).
URL:https://crc326gaus.de/event/agtz-kolloquium-4/
LOCATION:Mainz\, Hilbertraum (05-432)
CATEGORIES:GAUS-Seminar
ORGANIZER;CN="Georg Tamme":MAILTO:georg.tamme@uni-mainz.de
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20260529T140000
DTEND;TZID=Europe/Berlin:20260529T160000
DTSTAMP:20260619T213029
CREATED:20260518T070612Z
LAST-MODIFIED:20260518T070612Z
UID:13421-1780063200-1780070400@crc326gaus.de
SUMMARY:Membranes and Maps
DESCRIPTION:In joint work with A. Brini\, it was conjectured that equivariant Gromov–Witten invariants of Calabi–Yau fivefolds are governed by so-called membrane indices. When the fivefold is a product of a Calabi–Yau threefold and the affine plane\, the latter invariants agree with\, or refine\, Gopakumar–Vafa invariants. I will present evidence for the conjecture. Moreover\, I will explain how the numerical correspondence informs us about a possible modular interpretation of M2-branes since ultimately their moduli space should give rise to membrane indices. Building on ideas of Nekrasov and Okounkov\, I will propose a geometric interpretation of M2-branes in some concrete situations. I will then translate this proposal into formulas for Hodge integrals\, which can be verified in certain limits. This is based on work in progress with A. Giacchetto and R. Pandharipande.
URL:https://crc326gaus.de/event/membranes-and-maps/
LOCATION:Heidelberg\, MATHEMATIKON\, SR 007\, Im Neuenheimer Feld 205\, Heidelberg\, 69120\, Germany
CATEGORIES:GAUS-Seminar
ORGANIZER;CN="Georg Bernhard Oberdieck":MAILTO:georgo@uni-heidelberg.de
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20260529T153000
DTEND;TZID=Europe/Berlin:20260529T170000
DTSTAMP:20260619T213029
CREATED:20260319T100223Z
LAST-MODIFIED:20260422T125411Z
UID:12875-1780068600-1780074000@crc326gaus.de
SUMMARY:Seminar on Arithmetic Geometry
DESCRIPTION:Manuel Hoff (Bielefeld): Sheared displays and p-divisible groups \nAbstract: Let p be a prime and let R be a p-nilpotent ring. The theory of displays\, as developed by Zink and Lau\, gives an equivalence between infinitesimal p-divisible groups and V-nilpotent displays over R. The aim of the talk is to explain that general p-divisible groups are equivalent to sheared displays\, the analogue of displays where the ring of Witt vectors is replaced by its sheared version. This is joint work with Eike Lau. \nZoom (635 7328 0984\, Kenncode: kleinste sechsstellige Primzahl)
URL:https://crc326gaus.de/event/seminar-on-arithmetic-geometry-33/
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:20260611T141500
DTEND;TZID=Europe/Berlin:20260611T151500
DTSTAMP:20260619T213029
CREATED:20260529T092030Z
LAST-MODIFIED:20260605T084138Z
UID:13466-1781187300-1781190900@crc326gaus.de
SUMMARY:AGTZ Kolloquium
DESCRIPTION:Calla Tschanz (Uni Bochum) \nTitle:\nFrom logarithmic Hilbert schemes to degenerations of hyperkähler varieties \nAbstract:\nIn this talk\, I will discuss my previous work on constructing explicit models of logarithmic Hilbert schemes. This relates to work or Li-Wu on expanded degenerations\, Gulbrandsen-Halle-Hulek on degenerations of Hilbert schemes of points and Maulik-Ranganathan on logarithmic Hilbert schemes. The constructions I consider are local. I will then explain how we globalise these in joint work with Shafi and apply them to construct minimal type III degenerations of hyperkähler varieties\, namely Hilbert schemes of points on K3 surfaces.
URL:https://crc326gaus.de/event/agtz-kolloquium-5/
LOCATION:Mainz\, Hilbertraum (05-432)
CATEGORIES:GAUS-Seminar
ORGANIZER;CN="Georg Tamme":MAILTO:georg.tamme@uni-mainz.de
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20260612T133000
DTEND;TZID=Europe/Berlin:20260612T143000
DTSTAMP:20260619T213029
CREATED:20260507T081050Z
LAST-MODIFIED:20260507T081050Z
UID:13363-1781271000-1781274600@crc326gaus.de
SUMMARY:Eisenstein Congruences at Prime-Square Level
DESCRIPTION:Jaclyn Lang (Temple University Philadelphia) \nIn Mazur’s celebrated Eisenstein ideal paper\, he studies congruences between prime-level cusp forms and the unique weight-2 Eisenstein series of the same level. He shows that (if p is at least 5) such mod-p congruences exist if and only if the level N is congruent to 1 modulo p. In this talk\, we consider Eisenstein–cuspidal congruences in weight 2 and level N2\, still under the condition that N = 1 mod p. In this case\, recent work with Pollack and Wake shows that the relevant level-N2 Hecke algebra is a free module over an appropriate inertia-at-N pseudodeformation ring. This structure turns out to be surprisingly powerful. One can recover Mazur’s existence theorem that there exists a mod-p Eisenstein–cuspidal congruence in weight 2 and prime level N when N = 1 mod p. One can also recover the results of Merel and Lecouturier that characterize the rank of Mazur’s Hecke algebra in terms of the order of vanishing of a certain zeta element in cases when that rank is at most 3.  We will discuss some of the ideas that go into these results.  In addition to the joint work with Pollack and Wake\, the later results are joint with Palvannan and Müller.
URL:https://crc326gaus.de/event/eisenstein-congruences-at-prime-square-level/
LOCATION:Heidelberg\, Mathematikon\, SR A and Livestream
CATEGORIES:GAUS-Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20260612T140000
DTEND;TZID=Europe/Berlin:20260612T160000
DTSTAMP:20260619T213029
CREATED:20260608T111700Z
LAST-MODIFIED:20260608T111700Z
UID:13521-1781272800-1781280000@crc326gaus.de
SUMMARY:Crossed instantons in algebraic geometry
DESCRIPTION:In a series of papers\, Nekrasov introduces moduli spaces of “crossed instantons\,” certain quiver representations modeling instantons on unions of 2-planes in 4-space. The geometry of these spaces encodes information about moduli of sheaves on surfaces and produces deformations of characters of quantum affine algebras. In work with Martijn Kool and Woonam Lim\, we study Nekrasov’s moduli spaces from the perspective of algebraic geometry. I’ll explain how invariants of moduli spaces of crossed instantons can be defined using a construction from sheaf-counting on Calabi-Yai 4-folds. I’ll also state a speculative description of these spaces as moduli spaces of framed sheaves on a projective 4-fold.
URL:https://crc326gaus.de/event/crossed-instantons-in-algebraic-geometry/
LOCATION:Heidelberg\, MATHEMATIKON\, SR 007\, Im Neuenheimer Feld 205\, Heidelberg\, 69120\, Germany
CATEGORIES:GAUS-Seminar
ORGANIZER;CN="Georg Bernhard Oberdieck":MAILTO:georgo@uni-heidelberg.de
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20260612T153000
DTEND;TZID=Europe/Berlin:20260612T170000
DTSTAMP:20260619T213029
CREATED:20260319T100329Z
LAST-MODIFIED:20260319T100329Z
UID:12877-1781278200-1781283600@crc326gaus.de
SUMMARY:Seminar on Arithmetic Geometry
DESCRIPTION:Federico Binda (Milano): tba \nZoom (635 7328 0984\, Kenncode: kleinste sechsstellige Primzahl)
URL:https://crc326gaus.de/event/seminar-on-arithmetic-geometry-34/
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:20260618T140000
DTEND;TZID=Europe/Berlin:20260618T160000
DTSTAMP:20260619T213029
CREATED:20260608T111855Z
LAST-MODIFIED:20260608T111855Z
UID:13523-1781791200-1781798400@crc326gaus.de
SUMMARY:Cohomology of symmetric stacks
DESCRIPTION:I will talk about a joint project with Chenjing Bu\, Ben Davison\, Andrés Ibáñez-Núñez\, and Tasuki Kinko. For a large class of stacks\, we decompose their cohomology in terms of what we call BPS cohomology\, which is a structure originating in enumerative geometry of Calabi-Yau 3-folds\, but which is of interest beyond this class of examples. Such stacks include smooth stacks (such as the moduli of G-bundles on a curve)\, symplectic stacks (such as the moduli of G-Higgs bundle on a curve)\, or some (-1)-shifted symplectic stacks (such as the moduli of semistable sheaves on a Calabi-Yau threefold).
URL:https://crc326gaus.de/event/cohomology-of-symmetric-stacks/
LOCATION:Heidelberg\, MATHEMATIKON\, SR 007\, Im Neuenheimer Feld 205\, Heidelberg\, 69120\, Germany
CATEGORIES:GAUS-Seminar
ORGANIZER;CN="Georg Bernhard Oberdieck":MAILTO:georgo@uni-heidelberg.de
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20260618T160000
DTEND;TZID=Europe/Berlin:20260618T180000
DTSTAMP:20260619T213029
CREATED:20260612T095116Z
LAST-MODIFIED:20260612T100534Z
UID:13546-1781798400-1781805600@crc326gaus.de
SUMMARY:Oberseminar Algebra und Geometrie
DESCRIPTION:Dr. Giusi Capobianco: Algebraic and tropical Prym-Torelli map \nAbstract: Given an étale double cover of smooth curves one can associate a principally polarized abelian variety called the Prym variety. The map from the moduli space of double covers Rg to the moduli space of pp abelian varieties Ag-1 is called Prym-Torelli\, in analogy with the Jacobian case. This map does not extend to a morphism from the boundary of Rg to any of the standard toroidal compactifications of Ag-1. In this talk I will present their tropical counterpart and prove that\, with a slight modification of the definition\, the tropical Prym-Torelli map is continuous.\nThis result is part of my PhD thesis and will appear on the arXiv soon.
URL:https://crc326gaus.de/event/oberseminar-algebra-und-geometrie-9/
LOCATION:Frankfurt\, RM-Str. 6-8\, R. 308
CATEGORIES:GAUS-Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20260618T163000
DTEND;TZID=Europe/Berlin:20260618T173000
DTSTAMP:20260619T213029
CREATED:20260529T092153Z
LAST-MODIFIED:20260612T101403Z
UID:13468-1781800200-1781803800@crc326gaus.de
SUMMARY:AGTZ Kolloquium
DESCRIPTION:Karin Schaller (JGU Mainz) \nTitel: Nobodies are perfect\, semigroups are not. \nNewton-Okounkov bodies provide a powerful link between algebraic geometry and convex geometry\, extending the correspondence between toric varieties and lattice polytopes. They are constructed from valuation semigroups associated with divisors\, making the finite generation of these semigroups a natural and important question. After an introduction to toric geometry\, we study valuation semigroups on toric surfaces arising from non-toric flags. Based on joint work with Altmann\, Haase\, Küronya\, and Walter\, the talk presents a combinatorial criterion for the finite generation of these semigroups.
URL:https://crc326gaus.de/event/agtz-kolloquium-6/
LOCATION:Mainz\, Hilbertraum (05-432)
CATEGORIES:GAUS-Seminar
ORGANIZER;CN="Georg Tamme":MAILTO:georg.tamme@uni-mainz.de
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20260619T133000
DTEND;TZID=Europe/Berlin:20260619T143000
DTSTAMP:20260619T213029
CREATED:20260519T104110Z
LAST-MODIFIED:20260519T104110Z
UID:13427-1781875800-1781879400@crc326gaus.de
SUMMARY:On arithmetical surjectivity and the Conjecture of Colliot-Thelene
DESCRIPTION:Florian Pop (University of Pennsylvania) \nThe notion of ‘arithmetical surjectivity’ (a.s.) for dominant morphisms f of proper smooth varieties over number fields was introduced by Colliot-Thelene\, and he made a precise\nconjecture (CCT) relating a.s. to birational properties of the morphisms f. The CCT was proved in a sharper form by Denef (2019)\, and Loughran-Skorobogatov-Smeets gave a\ncharacterization of a.s. (2020). I will present a new method of proof which allows generalizations/refinements of the above results by: First\, allowing k to be any finitely generated base fields k with char(k)=0 (and beyond). Second\, showing that a.s. is a fully birational property\, i.e.\, a.s. depends only on properties of the function field extension defined by morphisms f. The method of proof also yields generalizations of the so called\nzero-cycle surjectivity\, considered/characterized over number fields by Gvirtz (2020).\nNOTE: The problems are completely open in positive characteristic!
URL:https://crc326gaus.de/event/on-arithmetical-surjectivity-and-the-conjecture-of-colliot-thelene/
LOCATION:Heidelberg\, Mathematikon\, SR A and Livestream
CATEGORIES:GAUS-Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20260619T153000
DTEND;TZID=Europe/Berlin:20260619T170000
DTSTAMP:20260619T213029
CREATED:20260319T100422Z
LAST-MODIFIED:20260520T110437Z
UID:12879-1781883000-1781888400@crc326gaus.de
SUMMARY:Seminar on Arithmetic Geometry
DESCRIPTION:Louisa Bröring (Duisburg-Essen): Quadratic Euler Characteristic of Geometrically Cyclic Branched Coverings \nThe quadratic Euler characteristic $\chi(X)$ of a smooth\, projective scheme\n$X$ over a field $k$ of characteristic not two is a refinement of the\ntopological Euler characteristic to quadratic forms\, constructed using motivic\nhomotopy theory. For example\, if $k\subset \mathbb{R}$\, then rank of $\chi(X)$\nis equal to the topological Euler characteristic of $X(\mathbb{C})$ and the\nsignature of $\chi(X)$ with respect to the given embedding is equal to the\ntopological Euler characteristic of $X(\mathbb{R})$. The quadratic Euler\ncharacteristic plays an import role in the programme of $\mathbb{A}^1$-refined\nenumerative geometry. \nAfter briefly introducing the quadratic Euler characteristic\, we present a\ncomputation of the quadratic Euler characteristic of geometrically cyclic\nbranched coverings leveraging Levine’s quadratic Riemann-Hurwitz formula. An\n$n$-fold geometrically cyclic branched covering is a morphism $f\colon Y \to\nX$ between smooth\, projective schemes together with a smooth\, closed subscheme\n$Z \subset X$ satisfying the following condition: there exists a line bundle\n$L$ over $X$ and a section $s \colon X \to L^{\otimes n}$ such that $Z$ is the\nzero locus of $s$ and $f$ is the pullback along $s$ of the map $L \to\nL^{\otimes n}$ taking $n$-th powers. \nAs an application\, we compute the quadratic Euler characteristic of branched\ndouble covers of $\mathbb{P}^2$\, which includes some K3 surfaces. \nZoom (635 7328 0984\, Kenncode: kleinste sechsstellige Primzahl)
URL:https://crc326gaus.de/event/seminar-on-arithmetic-geometry-35/
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:20260624T140000
DTEND;TZID=Europe/Berlin:20260624T160000
DTSTAMP:20260619T213029
CREATED:20260616T062328Z
LAST-MODIFIED:20260616T062328Z
UID:13585-1782309600-1782316800@crc326gaus.de
SUMMARY:Oberseminar Algebra und Geometrie
DESCRIPTION:Jonas Heintze (Universität Bonn): Poincare duality for Fargues Fontaine curve with almost coefficients \nAbstract: The Fargues-Fontaine curve is a central geometric object in modern approaches to p-adic Hodge theory. In this talk\, we will sketch ongoing work aimed at establishing Poincaré duality for the Fargues-Fontaine curve(s) viewed as analytic stacks using almost mathematics. This work is closely related to recent work of Anschütz\, Le Bras\, and Mann. \n  \n 
URL:https://crc326gaus.de/event/oberseminar-algebra-und-geometrie-10/
LOCATION:Frankfurt\, Robert-Mayer-Str. 6-8\, Raum 308
CATEGORIES:GAUS-Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20260625T141500
DTEND;TZID=Europe/Berlin:20260625T151500
DTSTAMP:20260619T213029
CREATED:20260529T092432Z
LAST-MODIFIED:20260616T115630Z
UID:13471-1782396900-1782400500@crc326gaus.de
SUMMARY:AGTZ Kolloquium
DESCRIPTION:Shai Keidar (Uni Regensburg) \nTitle: pi-finite Galois theory \nAbstract: In the higher-categorical world\, Galois theory extends beyond finite groups: one can study Galois extensions for an arbitrary E_1-group. We develop such a theory for higher semiadditive categories\, where finite groups are naturally replaced by pi-finite groups. Under height assumptions\, we construct an n-truncated pro-pi-finite “absolute Galois group” representing all Galois extensions\, and develop a higher Kummer theory relating abelian extensions to the Picard spectrum. As an illustration\, we attach a pro-pi-finite Galois space to a rational Stefanich ring and give an algorithm computing it.
URL:https://crc326gaus.de/event/agtz-kolloquium-7/
LOCATION:Mainz\, Hilbertraum (05-432)
CATEGORIES:GAUS-Seminar
ORGANIZER;CN="Georg Tamme":MAILTO:georg.tamme@uni-mainz.de
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BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20260626T133000
DTEND;TZID=Europe/Berlin:20260626T143000
DTSTAMP:20260619T213029
CREATED:20260519T090513Z
LAST-MODIFIED:20260521T093535Z
UID:13425-1782480600-1782484200@crc326gaus.de
SUMMARY:Elliptic curves attached to abelian threefolds with imaginary multiplication
DESCRIPTION:Pip Goodman (University of Barcelona) \nLet A be an abelian threefold defined over a number field K whose endomorphism algebra is isomorphic to an imaginary quadratic field M. In recent joint work with Fité\, we proved the existence of an elliptic curve E defined over K with CM by M such that for any prime \ell\, the twisted Tate module V_\ell(E) (1)  is a sub representation of \wedge^3 V_\ell(A).\nIn this talk I will give an overview of the proof of the above result and present work in progress with Chidambaram and Fité where we provide explicit families of examples of the above phenomenon.
URL:https://crc326gaus.de/event/elliptic-curves-attached-to-abelian-threefolds-with-imaginary-multiplication/
LOCATION:Heidelberg\, Mathematikon\, SR A and Livestream
CATEGORIES:GAUS-Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20260626T140000
DTEND;TZID=Europe/Berlin:20260626T160000
DTSTAMP:20260619T213029
CREATED:20260615T070624Z
LAST-MODIFIED:20260615T070624Z
UID:13580-1782482400-1782489600@crc326gaus.de
SUMMARY:The Morrison-Kawamata-Cone conjecture for Enriques surfaces in any characteristic
DESCRIPTION:Let X be a normal projective variety over an algebraically closed field and with numerically trivial canonical bundle\, for instance a Calabi-Yau manifold. The Morrison – Kawamata cone conjecture predicts that the automorphism group of X acts with a rational polyhedral fundamental domain on the effective nef cone of X. We give a new proof of the Morrison–Kawamata cone conjecture for Enriques surfaces independent of their characteristic. It is based on the analysis of certain generically finite morphisms of degree two. This is joint work with Gebhard Martin and Tobias Schnieders.
URL:https://crc326gaus.de/event/the-morrison-kawamata-cone-conjecture-for-enriques-surfaces-in-any-characteristic/
LOCATION:Heidelberg\, MATHEMATIKON\, SR 007\, Im Neuenheimer Feld 205\, Heidelberg\, 69120\, Germany
CATEGORIES:GAUS-Seminar
ORGANIZER;CN="Georg Bernhard Oberdieck":MAILTO:georgo@uni-heidelberg.de
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20260626T143000
DTEND;TZID=Europe/Berlin:20260626T163000
DTSTAMP:20260619T213029
CREATED:20260427T115524Z
LAST-MODIFIED:20260619T073142Z
UID:13242-1782484200-1782491400@crc326gaus.de
SUMMARY:Seminar on Arithmetic Geometry
DESCRIPTION:Konstantin Jakob (Darmstadt): Algebraic Loops and Stokes Braids \nThe irregular class of a rank n differential equation with an irregular singularity may be viewed as a polynomial map to the configuration space of n points. Such irregular classes feature prominently in Boalch’s construction of wild character varieties\, which are Betti moduli spaces for irregular connections. As the local coordinate winds around the singularity\, the irregular class describes the motion of eigenvalues of leading terms; this motion determines a braid\, called the Stokes braid. \nI will report on joint work with Masoud Kamgarpour and Ian Le in which we classify braids arising from such algebraic loops in terms of valuation data. I will explain why tropical geometry provides the natural language for this question\, and\, if time permits\, outline relations to several phenomena where the geometry or cohomology of spaces such as braid varieties is expected to depend only on tropical data. \nBitte früheren Beginn um 14:30 beachten.\nZoom (635 7328 0984\, Kenncode: kleinste sechsstellige Primzahl)
URL:https://crc326gaus.de/event/seminar-on-arithmetic-geometry-39/
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:20260701T164500
DTEND;TZID=Europe/Berlin:20260701T180000
DTSTAMP:20260619T213029
CREATED:20260618T074712Z
LAST-MODIFIED:20260618T095221Z
UID:13613-1782924300-1782928800@crc326gaus.de
SUMMARY:Transfer theorems between fields of different characteristic — a model-theoretic approach
DESCRIPTION:Franziska Jahnke (Universität Münster) \nFrankfurter Seminar \nAbstract: Under which circumstances can we use insights about fields of positive characteristic to understand fields of characteristic 0 (and conversely)?\nClassical methods to transfer results between fields of different  characteristics are the Lefshetz principle and the Ax Kochen/Ershov Theorem which states that asymptotically\, the theory of the p-adic numbers ℚp and of power series fields 𝔽p((t)) coincide. Tilting perfectoid fields gives a transfer principle between certain henselian fields of mixed characteristic and their positive characteristic counterparts and vice versa. In this talk\, we survey various transfer principles and present a model-theoretic approach to tilting via ultraproducts\, which allows us to transfer many first-order properties between a perfectoid field and its tilt. \n 
URL:https://crc326gaus.de/event/transfer-theorems-between-fields-of-different-characteristic-a-model-theoretic-approach/
LOCATION:Frankfurt\, Robert-Mayer-Str. 10\, Raum 711 groß
CATEGORIES:GAUS-Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20260702T141500
DTEND;TZID=Europe/Berlin:20260702T151500
DTSTAMP:20260619T213029
CREATED:20260529T093017Z
LAST-MODIFIED:20260529T093017Z
UID:13473-1783001700-1783005300@crc326gaus.de
SUMMARY:AGTZ Kolloquium
DESCRIPTION:Markus Spitzweg (Uni Osnabrück)
URL:https://crc326gaus.de/event/agtz-kolloquium-8/
LOCATION:Mainz\, Hilbertraum (05-432)
CATEGORIES:GAUS-Seminar
ORGANIZER;CN="Georg Tamme":MAILTO:georg.tamme@uni-mainz.de
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20260703T153000
DTEND;TZID=Europe/Berlin:20260703T170000
DTSTAMP:20260619T213029
CREATED:20260319T100517Z
LAST-MODIFIED:20260319T100517Z
UID:12881-1783092600-1783098000@crc326gaus.de
SUMMARY:Seminar on Arithmetic Geometry
DESCRIPTION:Yujie Xu (Columbia): tba \nZoom (635 7328 0984\, Kenncode: kleinste sechsstellige Primzahl)
URL:https://crc326gaus.de/event/seminar-on-arithmetic-geometry-36/
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:20260709T141500
DTEND;TZID=Europe/Berlin:20260709T151500
DTSTAMP:20260619T213029
CREATED:20260529T093132Z
LAST-MODIFIED:20260529T093132Z
UID:13475-1783606500-1783610100@crc326gaus.de
SUMMARY:AGTZ Kolloquium
DESCRIPTION:Konstantin Emming (Uni Bonn)
URL:https://crc326gaus.de/event/agtz-kolloquium-9/
LOCATION:Mainz\, Hilbertraum (05-432)
CATEGORIES:GAUS-Seminar
ORGANIZER;CN="Georg Tamme":MAILTO:georg.tamme@uni-mainz.de
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20260710T133000
DTEND;TZID=Europe/Berlin:20260710T143000
DTSTAMP:20260619T213029
CREATED:20260618T075048Z
LAST-MODIFIED:20260618T075048Z
UID:13617-1783690200-1783693800@crc326gaus.de
SUMMARY:p-adic singular moduli and higher Green’s functions
DESCRIPTION:Hazem Hassan (Heidelberg) \n\nHeegner cycles are the higher weight analogues to Heegner points. Those points and cycles play an important role in the theory of complex multiplication and of the arithmetic of elliptic curves of rank 1. Stark-Heegner points are conjectural points on elliptic curves which would be the real-quadratic counterparts to Heegner points in the emerging theory of real multiplication. In this theory\, Darmon-Vonk’s rigid meromorphic cocycles seem to be the real-quadratic analogue of singular moduli.\n\nI will present a generalization of rigid meromorphic cocycles to higher weight and use it to define a p-adic higher Green’s functions on real-quadratic points. This construction is motivated by the recently resolved conjecture by Gross and Zagier  on the algebraicity of values of complex higher Green’s functions. I will present a conjecture on the algebraicity of values of the p-adic Green’s functions that has been numerically verified. The values of the p-adic Green’s function are best envisioned as p-adic local intersection numbers of certain conjectured cycles associated to RM-points\, the so-called Stark-Heegner cycles.
URL:https://crc326gaus.de/event/p-adic-singular-moduli-and-higher-greens-functions/
LOCATION:Heidelberg\, Mathematikon\, SR A and Livestream
CATEGORIES:GAUS-Seminar
END:VEVENT
END:VCALENDAR