BEGIN:VCALENDAR VERSION:2.0 PRODID:researchseminars.org CALSCALE:GREGORIAN X-WR-CALNAME:researchseminars.org BEGIN:VEVENT SUMMARY:Sobhan Seyfaddini (Sorbonne) DTSTART:20210913T080000Z DTEND:20210913T090000Z DTSTAMP:20260422T213050Z UID:CGP_symplectic_seminar/1 DESCRIPTION:Title: The algebraic structure of groups of area-preserving homeom orphisms\nby Sobhan Seyfaddini (Sorbonne) as part of IBS-CGP weekly zo om seminar (Fall 2021)\n\nLecture held in Zoom online.\n\nAbstract\nI will review recent joint work with Dan Cristofaro-Gardiner\, Vincent Humilièr e\, Cheuk Yu Mak and Ivan Smith constructing a new family of spectral inva riants associated to certain Lagrangian links in compact and connected sur faces of any genus. We show that our invariants recover the Calabi invaria nt of Hamiltonians in their limit. As applications\, we resolve several op en questions from topological surface dynamics and continuous symplectic t opology: \n1. We show that the group of Hamiltonian homeomorphisms of any compact surface with (possibly empty) boundary is not simple\n2. We extend the Calabi homomorphism to the group of Hameomorphisms constructed by Oh- Müller.\n3. We construct an infinite dimensional family of quasimorphisms on the group of area and orientation preserving homeomorphisms of the two -sphere. \nOur invariants are inspired by recent work of Polterovich and S helukhin defining and applying spectral invariants for links in the two-sp here consisting of parallel circles.\n LOCATION:https://researchseminars.org/talk/CGP_symplectic_seminar/1/ END:VEVENT BEGIN:VEVENT SUMMARY:Siu-Cheong Lau (Boston) DTSTART:20211018T010000Z DTEND:20211018T020000Z DTSTAMP:20260422T213050Z UID:CGP_symplectic_seminar/3 DESCRIPTION:Title: Noncommutative deformations of crepant resolutions via mirr or symmetry\nby Siu-Cheong Lau (Boston) as part of IBS-CGP weekly zoom seminar (Fall 2021)\n\nLecture held in Zoom online.\n\nAbstract\nNoncommu tative crepant resolutions of singularities formulated by Van den Bergh ad mit interesting quantization deformations. On the other hand\, nc deforma tions can also be constructed via a local-to-global approach using the not ion of an algebroid stack. In this talk\, I will explain a mirror method of constructing explicit nc deformed crepant resolutions\, and a Fourier-M ukai transform between these two notions. An important ingredient is a ce rtain class of Lagrangian objects in the mirror side\, whose (higher) morp hisms can be found via a 3d enhancement of the corresponding objects in Ri emann surfaces.\n LOCATION:https://researchseminars.org/talk/CGP_symplectic_seminar/3/ END:VEVENT BEGIN:VEVENT SUMMARY:Daniel Anthony Gardiner (UCSC) DTSTART:20211101T010000Z DTEND:20211101T020000Z DTSTAMP:20260422T213050Z UID:CGP_symplectic_seminar/4 DESCRIPTION:Title: The Simplicity Conjecture\nby Daniel Anthony Gardiner ( UCSC) as part of IBS-CGP weekly zoom seminar (Fall 2021)\n\nLecture held i n Zoom online.\n\nAbstract\nIn the 60s and 70s\, there was a flurry of act ivity concerning the question of whether or not various subgroups of homeo morphism groups of manifolds are simple\, with beautiful contributions by Fathi\, Kirby\, Mather\, Thurston\, and many others. A funnily stubborn ca se that remained open was the case of area-preserving homeomorphisms of su rfaces. For example\, for balls of dimension at least 3\, the relevant gro up was shown to be simple by work of Fathi from the 1970s\, but the answer in the two-dimensional case was not known. I will explain recent joint wo rk proving that the group of compactly supported area preserving homeomorp hisms of the two-disc is in fact not a simple group\, which answers the "S implicity Conjecture” in the affirmative. Our proof uses a new tool for studying area-preserving surface homeomorphisms\, called periodic Floer ho mology (PFH) spectral invariants\; these recover the classical Calabi inva riant in their asymptotic limit.\n LOCATION:https://researchseminars.org/talk/CGP_symplectic_seminar/4/ END:VEVENT BEGIN:VEVENT SUMMARY:Kyungmin Rho (SNU (Seoul National University)) DTSTART:20210906T010000Z DTEND:20210906T020000Z DTSTAMP:20260422T213050Z UID:CGP_symplectic_seminar/5 DESCRIPTION:Title: Mirror Symmetry Correspondence between Indecomposable Cohen -Macaulay Modules over Degenerate Cusps and Immersed Lagrangians on Surfac es\nby Kyungmin Rho (SNU (Seoul National University)) as part of IBS-C GP weekly zoom seminar (Fall 2021)\n\nLecture held in Zoom online.\n\nAbst ract\nBurban and Drozd (2017) classified all indecomposable maximal Cohen- Macaulay modules over degenerate cusps. For the degenerate cusp defined by xyz\, its mirror is given by a pair of pants (Abouzaid\, Auroux\, Efimov\ , Katzarkov and Orlov). We find explicit objects in the Fukaya category of a pair of pants\, which correspond to every indecomposable Cohen-Macaulay modules in Burban and Drozd's list under the localized mirror functor. Th is is a joint work in progress with Cheol-Hyun Cho\, Wonbo Jeong and Kyoun gmo Kim.\n LOCATION:https://researchseminars.org/talk/CGP_symplectic_seminar/5/ END:VEVENT BEGIN:VEVENT SUMMARY:Tobias Ekholm (Uppsala) DTSTART:20210927T080000Z DTEND:20210927T090000Z DTSTAMP:20260422T213050Z UID:CGP_symplectic_seminar/6 DESCRIPTION:Title: Skein valued curve counts\, basic holomorphic disks\, and H OMFLY homology\nby Tobias Ekholm (Uppsala) as part of IBS-CGP weekly z oom seminar (Fall 2021)\n\nLecture held in Zoom online.\n\nAbstract\nWe de scribe invariant counts of holomorphic curves in a Calabi-Yau 3-fold with boundary in a Lagrangian in the skein module of that Lagrangian. We show how to turn this into concrete counts for the toric brane in the resolved conifold. This leads to a notion of basic holomorphic disks for any knot c onormal in the resolved conifold. These basic holomorphic disks seem to ge nerate HOMFLY homology in the basic representation. We give a conjectural description of similar holomorphic object generating parts of higher symme tric representation HOMFLY homology and verify some predictions coming fro m this conjecture in examples.\n LOCATION:https://researchseminars.org/talk/CGP_symplectic_seminar/6/ END:VEVENT BEGIN:VEVENT SUMMARY:Sheel Ganatra (USC) DTSTART:20211025T010000Z DTEND:20211025T020000Z DTSTAMP:20260422T213050Z UID:CGP_symplectic_seminar/7 DESCRIPTION:Title: Categorical non-properness in wrapped Floer theory\nby Sheel Ganatra (USC) as part of IBS-CGP weekly zoom seminar (Fall 2021)\n\n Lecture held in Zoom online.\n\nAbstract\nIn all known explicit computatio ns on Weinstein manifolds\, the self-wrapped Floer homology of non-compact exact Lagrangian is always either infinite-dimensional or zero. We will explain why a global variant of this observed phenomenon holds in broad ge nerality: the wrapped Fukaya category of any positive-dimensional Weinstei n (or non-degenerate Liouville) manifold is always either non-proper or ze ro\, as is any quotient thereof. Moreover any non-compact connected exact Lagrangian is always either a "non-proper object" or zero in such a wrappe d Fukaya category\, as is any idempotent summand thereof. We will examine where the argument could break if one drops exactness\, which is consisten t with known computations of non-exact wrapped Fukaya categories which are smooth\, proper\, and non-vanishing (e.g.\, work of Ritter-Smith). We wil l also give a perspective on the proof in terms of "properness obstruction " invariants of certain categories\, which can be related for wrapped Fuka ya categories to closed and open-string versions of Rabinowitz Floer theor y (the latter by joint work in progress with Y. Gao and S. Venkatesh).\n LOCATION:https://researchseminars.org/talk/CGP_symplectic_seminar/7/ END:VEVENT BEGIN:VEVENT SUMMARY:Mohammed Abouzaid (Colombia) DTSTART:20211108T010000Z DTEND:20211108T020000Z DTSTAMP:20260422T213050Z UID:CGP_symplectic_seminar/8 DESCRIPTION:Title: Complex cobordism and Hamiltonian fibrations\nby Mohamm ed Abouzaid (Colombia) as part of IBS-CGP weekly zoom seminar (Fall 2021)\ n\nLecture held in Zoom online.\n\nAbstract\nI will discuss joint work wit h McLean and Smith\, lifting the results of Seidel\, Lalonde\, and McDuff concerning the topology of Hamiltonian fibrations over the 2-sphere from r ational cohomology to complex cobordism. In addition to the use of Morava K-theory (as in the recent work with Blumberg on the Arnold Conjecture)\, the essential new ingredient is the construction of global Kuranishi chart s of genus 0 pseudo-holomorphic curves\; i.e. their realisation as quotie nts of zero loci of equivariant vector bundles on manifolds.\n LOCATION:https://researchseminars.org/talk/CGP_symplectic_seminar/8/ END:VEVENT BEGIN:VEVENT SUMMARY:Michael Usher (UGA) DTSTART:20211115T010000Z DTEND:20211115T020000Z DTSTAMP:20260422T213050Z UID:CGP_symplectic_seminar/9 DESCRIPTION:Title: Interlevel persistence and Floer theory\nby Michael Ush er (UGA) as part of IBS-CGP weekly zoom seminar (Fall 2021)\n\nLecture hel d in Zoom online.\n\nAbstract\nThere is a rich history in symplectic topol ogy of using the filtration structures on Floer complexes to extract geome trically interesting information\, in a way that formally mimics the relat ions between the homologies of sublevel sets of a Morse function on a fini te-dimensional manifold. In the finite-dimensional case\, it can be usefu l to consider homologies not just of sublevel sets but of interlevel sets (preimages of general intervals\, including singletons)\; however\, in the Floer-theoretic context it is not so obvious what the analogue of the hom ology of an interlevel set is. I will explain a general algebraic framewo rk---applicable for instance to Hamiltonian Floer theory---for obtaining i nterlevel persistence-type barcodes from the sorts of complexes that arise in Floer theory\; these barcodes carry somewhat more information than the more conventional sublevel persistence barcodes.\n LOCATION:https://researchseminars.org/talk/CGP_symplectic_seminar/9/ END:VEVENT BEGIN:VEVENT SUMMARY:Michael Hutchings (Berkeley) DTSTART:20211122T010000Z DTEND:20211122T020000Z DTSTAMP:20260422T213050Z UID:CGP_symplectic_seminar/10 DESCRIPTION:Title: Smooth closing lemmas for area-preserving surface diffeomo rphisms\nby Michael Hutchings (Berkeley) as part of IBS-CGP weekly zoo m seminar (Fall 2021)\n\nLecture held in Zoom online.\n\nAbstract\nWe show that an area-preserving diffeomorphism of a closed surface satisfying a " rationality" property has the "C^\\infty closing property". The latter pro perty asserts that for any nonempty open set\, one can make a C^\\infty sm all Hamiltonian perturbation supported in the open set to obtain a periodi c orbit intersecting the open set. Moreover we obtain quantitative results \, asserting roughly speaking that during a given Hamiltonian isotopy\, wi thin time \\delta a periodic orbit must appear of period at most O(\\delta ^{-1}). The proof uses spectral invariants in periodic Floer homology. Thi s is a joint work with Oliver Edtmair.\n LOCATION:https://researchseminars.org/talk/CGP_symplectic_seminar/10/ END:VEVENT BEGIN:VEVENT SUMMARY:Tony Yue Yu (Université Paris-Sud) DTSTART:20211129T010000Z DTEND:20211129T020000Z DTSTAMP:20260422T213050Z UID:CGP_symplectic_seminar/11 DESCRIPTION:Title: Moduli of Calabi-Yau pairs and secondary fans\nby Tony Yue Yu (Université Paris-Sud) as part of IBS-CGP weekly zoom seminar (Fa ll 2021)\n\nLecture held in Zoom online.\n\nAbstract\nWe conjecture that t he moduli space of smooth polarized Calabi-Yau pairs is unirational. More precisely\, we consider its natural compactification inside the KSBA stabl e pair moduli space\, and conjecture that the compactification admits a fi nite cover by a complete toric variety. We construct the associated comple te toric fan\, generalizing the Gelfand-Kapranov-Zelevinski secondary fan for reflexive polytopes. Inspired by mirror symmetry\, we speculate a synt hetic construction of the universal family over this toric variety\, as th e Proj of a sheaf of graded algebras with a canonical basis\, whose struct ure constants are given by counts of non-archimedean analytic disks. In th e Fano case and under the assumption that the mirror variety contains a Za riski open torus\, we construct the conjectural universal family\, general izing the families of Kapranov-Sturmfels-Zelevinski and Alexeev in the tor ic case. In the case of del Pezzo surfaces with an anti-canonical cycle of (-1)-curves\, we prove the full conjecture. Joint work with Hacking and K eel.\n LOCATION:https://researchseminars.org/talk/CGP_symplectic_seminar/11/ END:VEVENT BEGIN:VEVENT SUMMARY:Jeffrey Carlson (Imperial College London) DTSTART:20211206T080000Z DTEND:20211206T090000Z DTSTAMP:20260422T213050Z UID:CGP_symplectic_seminar/12 DESCRIPTION:Title: The topology of the Gelfand–Zeitlin fiber\nby Jeffre y Carlson (Imperial College London) as part of IBS-CGP weekly zoom seminar (Fall 2021)\n\nLecture held in Zoom online.\n\nAbstract\nGelfand–Zeitli n systems are a well-known family of examples in symplectic geometry\, sin gular Lagrangian torus fibrations whose total spaces are coadjoint orbits of an action of a unitary or special orthogonal group and whose base space s are certain convex polytopes. They are easily defined in terms of matric es and their truncations\, but do not fit into the familiar framework of i ntegrable systems with nondegenerate singularities\, and hence are studied as a sort of edge case.\n\nIt is known that the fibers of these systems a re determined as iterated pullbacks by the combinatorics of joint eigenval ues of systems of truncated matrices\, but the resulting expressions can b e rather inexplicit. We provide a new interpretation of Gelfand–Zeitlin fibers as balanced products of Lie groups (or biquotients)\, and pursue th ese viewpoints to a determination of their cohomology rings and low-dimens ional homotopy groups which can be read transparently off of the combinato rics.\n\n\nThis all represents joint work with Jeremy Lane.\n LOCATION:https://researchseminars.org/talk/CGP_symplectic_seminar/12/ END:VEVENT BEGIN:VEVENT SUMMARY:Naoki Fujita (University of Tokyo) DTSTART:20211213T010000Z DTEND:20211213T020000Z DTSTAMP:20260422T213050Z UID:CGP_symplectic_seminar/13 DESCRIPTION:Title: Semi-toric degenerations of Richardson varieties from clus ter algebras\nby Naoki Fujita (University of Tokyo) as part of IBS-CGP weekly zoom seminar (Fall 2021)\n\nLecture held in Zoom online.\n\nAbstra ct\nA toric degeneration is a flat degeneration into an irreducible normal toric variety. In the case of a flag variety\, its toric degeneration wit h desirable properties induces degenerations of Richardson varieties into unions of irreducible toric subvarieties\, called semi-toric degenerations . Semi-toric degenerations are closely related to Schubert calculus. For i nstance\, Kogan-Miller constructed semi-toric degenerations of Schubert va rieties from Knutson-Miller's semi-toric degenerations of matrix Schubert varieties which give a geometric proof of the pipe dream formula of Schube rt polynomials. In this talk\, we construct a toric degeneration of a flag variety using its cluster structure\, and see that it induces semi-toric degenerations of Richardson varieties\, which can be regarded as generaliz ations of Kogan-Miller's semi-toric degeneration. This talk is partly base d on a joint work with Hironori Oya.\n LOCATION:https://researchseminars.org/talk/CGP_symplectic_seminar/13/ END:VEVENT END:VCALENDAR