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PRODID:Mathematics Seminar Calendar
BEGIN:VEVENT
UID:20191206T083540-18593@math.msu.edu
DTSTAMP:20191206T083540Z
SUMMARY:Probing 4-manifolds with near-symplectic forms
DESCRIPTION:Speaker\: Chris Gerig, Harvard University \r\nMost closed 4-manifolds do not admit symplectic forms, but most admit "near-symplectic forms", certain closed 2-forms which are symplectic outside of a collection of circles. This provides a gateway from the symplectic world to the non-symplectic world. I will first briefly sketch a geometric interpretation of the Seiberg-Witten invariants in terms of J-holomorphic curves that are compatible with the near-symplectic form. Although the Seiberg-Witten invariants don't apply to (potentially exotic) 4-spheres, nor do these spheres admit near-symplectic forms, there is still a way to bring in near-symplectic techniques.
LOCATION:C304 Wells Hall
DTSTART:20190829T180000Z
DTEND:20190829T190000Z
URL:https://math.msu.edu/Seminars/TalkView.aspx?talk=18593
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UID:20191206T083540-19602@math.msu.edu
DTSTAMP:20191206T083540Z
SUMMARY:$G_2$-instantons on the 7-sphere
DESCRIPTION:Speaker\: Alex Waldron, Michigan State University \r\nI'll discuss a forthcoming paper studying families of $G_2$-instantons on $S^7$, focusing on those which are obtained by pulling back asd instantons on $S^4 $ via the quaternionic Hopf fibration. In the charge-1 case this yields a smooth and complete 15-dimensional family. The situation for higher charge is more complicated, but we are able to compute all the infinitesimal deformations.
LOCATION:C304 Wells Hall
DTSTART:20190905T180000Z
DTEND:20190905T190000Z
URL:https://math.msu.edu/Seminars/TalkView.aspx?talk=19602
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BEGIN:VEVENT
UID:20191206T083540-19635@math.msu.edu
DTSTAMP:20191206T083540Z
SUMMARY:Augmentations and sheaves for links
DESCRIPTION:Speaker\: Honghao Gao, MSU\r\nWe study two different invariants of framed oriented links. Augmentations are rank one representations of a non-commutative algebra, whose definition is motivated by Floer homology. Sheaves in microlocal theory can be thought of as generalizations of link group representations. We will demonstrate two constructions going back and forth between these invariants. We will also tell a motivating story behind the scene, using SFT and microlocalization correspondence in symplectic topology.
LOCATION:C304 Wells Hall
DTSTART:20190912T180000Z
DTEND:20190912T190000Z
URL:https://math.msu.edu/Seminars/TalkView.aspx?talk=19635
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BEGIN:VEVENT
UID:20191206T083540-18580@math.msu.edu
DTSTAMP:20191206T083540Z
SUMMARY:Holonomy perturbations of the Chern-Simons functional for lens spaces
DESCRIPTION:Speaker\: David Boozer, UCLA\r\nWe describe a scheme for constructing generating sets for Kronheimer and Mrowka's singular instanton knot homology for the case of knots in lens spaces. The scheme involves Heegaard-splitting a lens space containing a knot into two solid tori. One solid torus contains a portion of the knot consisting of an unknotted arc, as well as holonomy perturbations of the Chern-Simons functional used to define the homology theory. The other solid torus contains the remainder of the knot. The Heegaard splitting yields a pair of Lagrangians in the traceless $SU(2)$-character variety of the twice-punctured torus, and the intersection points of these Lagrangians comprise the generating set that we seek. We illustrate the scheme by constructing generating sets for several example knots. Our scheme is a direct generalization of a scheme introduced by Hedden, Herald, and Kirk for describing generating sets for knots in $S^3$ in terms of Lagrangian intersections in the traceless $SU(2)$-character variety for the 2-sphere with four punctures.
LOCATION:C304 Wells Hall
DTSTART:20190926T180000Z
DTEND:20190926T190000Z
URL:https://math.msu.edu/Seminars/TalkView.aspx?talk=18580
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BEGIN:VEVENT
UID:20191206T083540-18586@math.msu.edu
DTSTAMP:20191206T083540Z
SUMMARY:On Geodesic Triangles in the Hyperbolic Plane
DESCRIPTION:Speaker\: Rita Gitik, Michigan\r\nLet M be an orientable hyperbolic surface without boundary and\r\nlet c be a closed geodesic in M. We prove that any side of any triangle formed by distinct lifts of c in the hyperbolic plane is shorter than c. The talk will be presented for advanced undergraduate and beginning graduate students.\r\n
LOCATION:C304 Wells Hall
DTSTART:20191003T180000Z
DTEND:20191003T185000Z
URL:https://math.msu.edu/Seminars/TalkView.aspx?talk=18586
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BEGIN:VEVENT
UID:20191206T083540-19632@math.msu.edu
DTSTAMP:20191206T083540Z
SUMMARY:Bubble Tree Convergence of Parametrized Associative Submanifolds
DESCRIPTION:Speaker\: Jesse Madnick , McMaster University \r\nIn symplectic geometry, part of Gromov's Compactness Theorem asserts that sequences of holomorphic curves with bounded energy have subsequences that converge to bubble trees, and that both energy and homotopy are preserved in this "bubble tree limit." In $G_2$ geometry, the analogues of holomorphic maps are the "associative Smith maps." In this talk, we'll see that familiar analytic features of holomorphic maps also hold for associative Smith maps. In particular, we'll describe how sequences of associative Smith maps give rise to bubble trees, and how energy and homotopy are again preserved in the limit. This is joint work with Da Rong Cheng and Spiro Karigiannis.
LOCATION:C304 Wells Hall
DTSTART:20191017T180000Z
DTEND:20191017T190000Z
URL:https://math.msu.edu/Seminars/TalkView.aspx?talk=19632
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BEGIN:VEVENT
UID:20191206T083540-19641@math.msu.edu
DTSTAMP:20191206T083540Z
SUMMARY:Obstructing Lagrangian link cobordisms via Heegaard Floer homology.
DESCRIPTION:Speaker\: Lev Tovstopyat-Nelip, MSU\r\nI'll explain how an invariant of Legendrian links in knot Floer homology can be used to obstruct the existence of decomposable Lagrangian link cobordisms in a very general setting. The argument involves braiding the ends of the cobordism about open books and appealing to an algebraic property of the Legendrian invariant called comultiplication. Much of the talk will be spent describing the topological and contact geometric ingredients.
LOCATION:C304 Wells Hall
DTSTART:20191024T180000Z
DTEND:20191024T190000Z
URL:https://math.msu.edu/Seminars/TalkView.aspx?talk=19641
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BEGIN:VEVENT
UID:20191206T083540-19619@math.msu.edu
DTSTAMP:20191206T083540Z
SUMMARY:Classification of links with Khovanov homology of minimal rank
DESCRIPTION:Speaker\: Boyu Zhang, Princeton University\r\nIn this talk, I will present a classification of links whose Khovanov homology has minimal rank, which answers a question asked by Batson and Seed. The proof is based on an excision formula for singular instanton Floer homology that allows the excision surface to intersect the singularity. We will use the excision theorem to define an instanton Floer homology for tangles on sutured manifolds, and show that its gradings detect the generalized Thurston norm for punctured surfaces. This is joint work with Yi Xie.
LOCATION:C304 Wells Hall
DTSTART:20191031T180000Z
DTEND:20191031T190000Z
URL:https://math.msu.edu/Seminars/TalkView.aspx?talk=19619
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BEGIN:VEVENT
UID:20191206T083540-19628@math.msu.edu
DTSTAMP:20191206T083540Z
SUMMARY:Braid invariant relating knot Floer homology and Khovanov homology
DESCRIPTION:Speaker\: Akram Alishahi, University of Georgia\r\nKhovanov homology and knot Floer homology are two knot invariants that were defined around the same time, and despite their different constructions, share many formal similarities. After reviewing the construction of Khovanov homology and some of these similarities, we will discuss an algebraic braid invariant which is closely related to both Khovanov homology and the refinement of knot Floer homology into tangle invariants. This is a joint work with Nathan Dowlin.\r\n
LOCATION:C304 Wells Hall
DTSTART:20191121T190000Z
DTEND:20191121T200000Z
URL:https://math.msu.edu/Seminars/TalkView.aspx?talk=19628
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BEGIN:VEVENT
UID:20191206T083540-19621@math.msu.edu
DTSTAMP:20191206T083540Z
SUMMARY:Pure braids and link concordance
DESCRIPTION:Speaker\: Shelly Harvey, Rice\r\nIf one considers the set of m-component based links in R^3\r\nwith a 4-dimensional equivalence relationship on it, called\r\nconcordance, one can form a group called the link concordance group,\r\nC^m. Questions in concordance are important in for classification\r\nquestions in topological and smooth 4-manifolds It is well known that\r\nthe link concordance group contains the isotopy class of pure braid\r\nwith m strands, P_m. That is, two braids are concordant if and only\r\nif they are isotopic! In the late 90's Tim Cochran, Kent Orr, and\r\nPeter Teichner defined a filtration of the knot/link concordance group\r\ncalled the n-solvable filtration. This filtration gives a way to\r\napproximate whether a link is trivial in the group. We discuss the\r\nrelationship between pure braids and the n-solvable filtration as well\r\nas various other more geometrically defined filtrations coming from\r\ngropes and Whitney towers. This is joint work with Aru Ray and Jung\r\nHwan Park.
LOCATION:C304 Wells Hall
DTSTART:20191205T190000Z
DTEND:20191205T200000Z
URL:https://math.msu.edu/Seminars/TalkView.aspx?talk=19621
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BEGIN:VEVENT
UID:20191206T083540-20691@math.msu.edu
DTSTAMP:20191206T083540Z
SUMMARY:Price Inequalities and Benjamini-Schramm Convergence
DESCRIPTION:Speaker\: Luca Di Cerbo, University of Florida\r\nIn this talk, I will present a study of Betti numbers of sequences of compact negatively curved Riemannian manifolds Benjamini-Schramm converging to their universal covers. The main tools are a Price inequality for harmonic forms on negatively curved spaces, and an effective thick-thin decomposition.
LOCATION:C304 Wells Hall
DTSTART:20191210T160000Z
DTEND:20191210T170000Z
URL:https://math.msu.edu/Seminars/TalkView.aspx?talk=20691
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