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:20260404T111413Z UID:CGP_symplectic_seminar/1 DESCRIPTION:Title: The algebraic structure of groups of area-preserving homeomorphisms\nby Sobhan Seyfaddini (Sorbonne) as part of IBS-CGP we ekly zoom seminar (Fall 2021)\n\nLecture held in Zoom online.\n\nAbstract\ nI will review recent joint work with Dan Cristofaro-Gardiner\, Vincent Hu milière\, Cheuk Yu Mak and Ivan Smith constructing a new family of spectr al invariants associated to certain Lagrangian links in compact and connec ted surfaces of any genus. We show that our invariants recover the Calabi invariant of Hamiltonians in their limit. As applications\, we resolve sev eral open questions from topological surface dynamics and continuous sympl ectic topology: \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 quasimo rphisms on the group of area and orientation preserving homeomorphisms of the two-sphere. \nOur invariants are inspired by recent work of Polterovic h and Shelukhin defining and applying spectral invariants for links in the two-sphere consisting of parallel circles.\n LOCATION:https://stable.researchseminars.org/talk/CGP_symplectic_seminar/1 / END:VEVENT BEGIN:VEVENT SUMMARY:Siu-Cheong Lau (Boston) DTSTART:20211018T010000Z DTEND:20211018T020000Z DTSTAMP:20260404T111413Z UID:CGP_symplectic_seminar/3 DESCRIPTION:Title: Noncommutative deformations of crepant resolutions v ia mirror symmetry\nby Siu-Cheong Lau (Boston) as part of IBS-CGP week ly zoom seminar (Fall 2021)\n\nLecture held in Zoom online.\n\nAbstract\nN oncommutative crepant resolutions of singularities formulated by Van den B ergh admit interesting quantization deformations. On the other hand\, nc deformations can also be constructed via a local-to-global approach using the notion of an algebroid stack. In this talk\, I will explain a mirror method of constructing explicit nc deformed crepant resolutions\, and a Fo urier-Mukai transform between these two notions. An important ingredient is a certain class of Lagrangian objects in the mirror side\, whose (highe r) morphisms can be found via a 3d enhancement of the corresponding object s in Riemann surfaces.\n LOCATION:https://stable.researchseminars.org/talk/CGP_symplectic_seminar/3 / END:VEVENT BEGIN:VEVENT SUMMARY:Daniel Anthony Gardiner (UCSC) DTSTART:20211101T010000Z DTEND:20211101T020000Z DTSTAMP:20260404T111413Z UID:CGP_symplectic_seminar/4 DESCRIPTION:Title: The Simplicity Conjecture\nby Daniel Anthony Gar diner (UCSC) as part of IBS-CGP weekly zoom seminar (Fall 2021)\n\nLecture held in Zoom online.\n\nAbstract\nIn the 60s and 70s\, there was a flurry of activity concerning the question of whether or not various subgroups o f homeomorphism groups of manifolds are simple\, with beautiful contributi ons by Fathi\, Kirby\, Mather\, Thurston\, and many others. A funnily stub born case that remained open was the case of area-preserving homeomorphism s of surfaces. For example\, for balls of dimension at least 3\, the relev ant group 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 j oint work proving that the group of compactly supported area preserving ho meomorphisms of the two-disc is in fact not a simple group\, which answers the "Simplicity Conjecture” in the affirmative. Our proof uses a new to ol for studying area-preserving surface homeomorphisms\, called periodic F loer homology (PFH) spectral invariants\; these recover the classical Cala bi invariant in their asymptotic limit.\n LOCATION:https://stable.researchseminars.org/talk/CGP_symplectic_seminar/4 / END:VEVENT BEGIN:VEVENT SUMMARY:Kyungmin Rho (SNU (Seoul National University)) DTSTART:20210906T010000Z DTEND:20210906T020000Z DTSTAMP:20260404T111413Z UID:CGP_symplectic_seminar/5 DESCRIPTION:Title: Mirror Symmetry Correspondence between Indecomposabl e Cohen-Macaulay Modules over Degenerate Cusps and Immersed Lagrangians on Surfaces\nby Kyungmin Rho (SNU (Seoul National University)) as part o f IBS-CGP weekly zoom seminar (Fall 2021)\n\nLecture held in Zoom online.\ n\nAbstract\nBurban and Drozd (2017) classified all indecomposable maximal Cohen-Macaulay modules over degenerate cusps. For the degenerate cusp def ined by xyz\, its mirror is given by a pair of pants (Abouzaid\, Auroux\, Efimov\, Katzarkov and Orlov). We find explicit objects in the Fukaya cate gory of a pair of pants\, which correspond to every indecomposable Cohen-M acaulay modules in Burban and Drozd's list under the localized mirror func tor. This is a joint work in progress with Cheol-Hyun Cho\, Wonbo Jeong an d Kyoungmo Kim.\n LOCATION:https://stable.researchseminars.org/talk/CGP_symplectic_seminar/5 / END:VEVENT BEGIN:VEVENT SUMMARY:Tobias Ekholm (Uppsala) DTSTART:20210927T080000Z DTEND:20210927T090000Z DTSTAMP:20260404T111413Z UID:CGP_symplectic_seminar/6 DESCRIPTION:Title: Skein valued curve counts\, basic holomorphic disks\ , and HOMFLY homology\nby Tobias Ekholm (Uppsala) as part of IBS-CGP w eekly zoom seminar (Fall 2021)\n\nLecture held in Zoom online.\n\nAbstract \nWe describe invariant counts of holomorphic curves in a Calabi-Yau 3-fol d with boundary in a Lagrangian in the skein module of that Lagrangian. W e show how to turn this into concrete counts for the toric brane in the re solved conifold. This leads to a notion of basic holomorphic disks for any knot conormal in the resolved conifold. These basic holomorphic disks see m to generate HOMFLY homology in the basic representation. We give a conje ctural description of similar holomorphic object generating parts of highe r symmetric representation HOMFLY homology and verify some predictions com ing from this conjecture in examples.\n LOCATION:https://stable.researchseminars.org/talk/CGP_symplectic_seminar/6 / END:VEVENT BEGIN:VEVENT SUMMARY:Sheel Ganatra (USC) DTSTART:20211025T010000Z DTEND:20211025T020000Z DTSTAMP:20260404T111413Z 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 20 21)\n\nLecture held in Zoom online.\n\nAbstract\nIn all known explicit com putations on Weinstein manifolds\, the self-wrapped Floer homology of non- compact exact Lagrangian is always either infinite-dimensional or zero. W e will explain why a global variant of this observed phenomenon holds in b road generality: the wrapped Fukaya category of any positive-dimensional W einstein (or non-degenerate Liouville) manifold is always either non-prope r or zero\, as is any quotient thereof. Moreover any non-compact connected exact Lagrangian is always either a "non-proper object" or zero in such a wrapped Fukaya category\, as is any idempotent summand thereof. We will e xamine where the argument could break if one drops exactness\, which is co nsistent with known computations of non-exact wrapped Fukaya categories wh ich are smooth\, proper\, and non-vanishing (e.g.\, work of Ritter-Smith). We will also give a perspective on the proof in terms of "properness obst ruction" invariants of certain categories\, which can be related for wrapp ed Fukaya categories to closed and open-string versions of Rabinowitz Floe r theory (the latter by joint work in progress with Y. Gao and S. Venkates h).\n LOCATION:https://stable.researchseminars.org/talk/CGP_symplectic_seminar/7 / END:VEVENT BEGIN:VEVENT SUMMARY:Mohammed Abouzaid (Colombia) DTSTART:20211108T010000Z DTEND:20211108T020000Z DTSTAMP:20260404T111413Z UID:CGP_symplectic_seminar/8 DESCRIPTION:Title: Complex cobordism and Hamiltonian fibrations\nby Mohammed Abouzaid (Colombia) as part of IBS-CGP weekly zoom seminar (Fall 2021)\n\nLecture held in Zoom online.\n\nAbstract\nI will discuss joint w ork with McLean and Smith\, lifting the results of Seidel\, Lalonde\, and McDuff concerning the topology of Hamiltonian fibrations over the 2-sphere from rational cohomology to complex cobordism. In addition to the use of Morava K-theory (as in the recent work with Blumberg on the Arnold Conject ure)\, the essential new ingredient is the construction of global Kuranish i charts of genus 0 pseudo-holomorphic curves\; i.e. their realisation as quotients of zero loci of equivariant vector bundles on manifolds.\n LOCATION:https://stable.researchseminars.org/talk/CGP_symplectic_seminar/8 / END:VEVENT BEGIN:VEVENT SUMMARY:Michael Usher (UGA) DTSTART:20211115T010000Z DTEND:20211115T020000Z DTSTAMP:20260404T111413Z UID:CGP_symplectic_seminar/9 DESCRIPTION:Title: Interlevel persistence and Floer theory\nby Mich ael Usher (UGA) as part of IBS-CGP weekly zoom seminar (Fall 2021)\n\nLect ure held in Zoom online.\n\nAbstract\nThere is a rich history in symplecti c topology of using the filtration structures on Floer complexes to extrac t geometrically interesting information\, in a way that formally mimics th e relations between the homologies of sublevel sets of a Morse function on a finite-dimensional manifold. In the finite-dimensional case\, it can b e useful to consider homologies not just of sublevel sets but of interleve l sets (preimages of general intervals\, including singletons)\; however\, in the Floer-theoretic context it is not so obvious what the analogue of the homology of an interlevel set is. I will explain a general algebraic framework---applicable for instance to Hamiltonian Floer theory---for obta ining interlevel persistence-type barcodes from the sorts of complexes tha t arise in Floer theory\; these barcodes carry somewhat more information t han the more conventional sublevel persistence barcodes.\n LOCATION:https://stable.researchseminars.org/talk/CGP_symplectic_seminar/9 / END:VEVENT BEGIN:VEVENT SUMMARY:Michael Hutchings (Berkeley) DTSTART:20211122T010000Z DTEND:20211122T020000Z DTSTAMP:20260404T111413Z UID:CGP_symplectic_seminar/10 DESCRIPTION:Title: Smooth closing lemmas for area-preserving surface d iffeomorphisms\nby Michael Hutchings (Berkeley) as part of IBS-CGP wee kly zoom seminar (Fall 2021)\n\nLecture held in Zoom online.\n\nAbstract\n We show that an area-preserving diffeomorphism of a closed surface satisfy ing a "rationality" property has the "C^\\infty closing property". The lat ter property asserts that for any nonempty open set\, one can make a C^\\i nfty small Hamiltonian perturbation supported in the open set to obtain a periodic orbit intersecting the open set. Moreover we obtain quantitative results\, asserting roughly speaking that during a given Hamiltonian isoto py\, within time \\delta a periodic orbit must appear of period at most O( \\delta^{-1}). The proof uses spectral invariants in periodic Floer homolo gy. This is a joint work with Oliver Edtmair.\n LOCATION:https://stable.researchseminars.org/talk/CGP_symplectic_seminar/1 0/ END:VEVENT BEGIN:VEVENT SUMMARY:Tony Yue Yu (Université Paris-Sud) DTSTART:20211129T010000Z DTEND:20211129T020000Z DTSTAMP:20260404T111413Z UID:CGP_symplectic_seminar/11 DESCRIPTION:Title: Moduli of Calabi-Yau pairs and secondary fans\n by Tony Yue Yu (Université Paris-Sud) as part of IBS-CGP weekly zoom semi nar (Fall 2021)\n\nLecture held in Zoom online.\n\nAbstract\nWe conjecture that the moduli space of smooth polarized Calabi-Yau pairs is unirational . More precisely\, we consider its natural compactification inside the KSB A stable pair moduli space\, and conjecture that the compactification admi ts a finite cover by a complete toric variety. We construct the associated complete toric fan\, generalizing the Gelfand-Kapranov-Zelevinski seconda ry fan for reflexive polytopes. Inspired by mirror symmetry\, we speculate a synthetic construction of the universal family over this toric variety\ , as the Proj of a sheaf of graded algebras with a canonical basis\, whose structure constants are given by counts of non-archimedean analytic disks . In the Fano case and under the assumption that the mirror variety contai ns a Zariski open torus\, we construct the conjectural universal family\, generalizing the families of Kapranov-Sturmfels-Zelevinski and Alexeev in the toric case. In the case of del Pezzo surfaces with an anti-canonical c ycle of (-1)-curves\, we prove the full conjecture. Joint work with Hackin g and Keel.\n LOCATION:https://stable.researchseminars.org/talk/CGP_symplectic_seminar/1 1/ END:VEVENT BEGIN:VEVENT SUMMARY:Jeffrey Carlson (Imperial College London) DTSTART:20211206T080000Z DTEND:20211206T090000Z DTSTAMP:20260404T111413Z UID:CGP_symplectic_seminar/12 DESCRIPTION:Title: The topology of the Gelfand–Zeitlin fiber\nby Jeffrey Carlson (Imperial College London) as part of IBS-CGP weekly zoom seminar (Fall 2021)\n\nLecture held in Zoom online.\n\nAbstract\nGelfand –Zeitlin systems are a well-known family of examples in symplectic geome try\, singular Lagrangian torus fibrations whose total spaces are coadjoin t orbits of an action of a unitary or special orthogonal group and whose b ase spaces are certain convex polytopes. They are easily defined in terms of matrices and their truncations\, but do not fit into the familiar frame work of integrable systems with nondegenerate singularities\, and hence ar e studied as a sort of edge case.\n\nIt is known that the fibers of these systems are determined as iterated pullbacks by the combinatorics of joint eigenvalues of systems of truncated matrices\, but the resulting expressi ons can be rather inexplicit. We provide a new interpretation of Gelfand –Zeitlin fibers as balanced products of Lie groups (or biquotients)\, an d pursue these viewpoints to a determination of their cohomology rings and low-dimensional homotopy groups which can be read transparently off of th e combinatorics.\n\n\nThis all represents joint work with Jeremy Lane.\n LOCATION:https://stable.researchseminars.org/talk/CGP_symplectic_seminar/1 2/ END:VEVENT BEGIN:VEVENT SUMMARY:Naoki Fujita (University of Tokyo) DTSTART:20211213T010000Z DTEND:20211213T020000Z DTSTAMP:20260404T111413Z UID:CGP_symplectic_seminar/13 DESCRIPTION:Title: Semi-toric degenerations of Richardson varieties fr om cluster algebras\nby Naoki Fujita (University of Tokyo) as part of IBS-CGP weekly zoom seminar (Fall 2021)\n\nLecture held in Zoom online.\n\ nAbstract\nA toric degeneration is a flat degeneration into an irreducible normal toric variety. In the case of a flag variety\, its toric degenerat ion with desirable properties induces degenerations of Richardson varietie s into unions of irreducible toric subvarieties\, called semi-toric degene rations. Semi-toric degenerations are closely related to Schubert calculus . For instance\, Kogan-Miller constructed semi-toric degenerations of Schu bert varieties from Knutson-Miller's semi-toric degenerations of matrix Sc hubert varieties which give a geometric proof of the pipe dream formula of Schubert 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 ge neralizations of Kogan-Miller's semi-toric degeneration. This talk is part ly based on a joint work with Hironori Oya.\n LOCATION:https://stable.researchseminars.org/talk/CGP_symplectic_seminar/1 3/ END:VEVENT END:VCALENDAR