Mdtop

mdtop@mathdept.okstate.edu

247 discussions

Seminar this fall
by Hoffman, Neil 11 Aug '22

11 Aug '22

Hello everyone, I should start with you are going to get two messages from me today: one here and one to mdall. If you are getting this message, you are on the topology email list. We are going to meet this semester on Tuesdays from 3:30-4:30. Our default seminar will be in person. Let me know if this poses a problem. Our organizational meeting will be August 30th as August 23 has a faculty meeting. Finally, if you are getting this message and wish to get OFF the email list, let me know and I can take care of that for you. Best, Neil ______________________ Neil R. Hoffman Assistant Professor Department of Mathematics 523 Math Science Building Oklahoma State University Stillwater, OK 74078-1058 405-744-7791 http://math.okstate.edu/people/nhoffman

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Topology seminar tomorrow
by Hoffman, Neil 25 Apr '22

25 Apr '22

Hello everyone, Tomorrow, we have our final speaker of the semester, Cameron Rudd. Title: Computing a link diagram from its exterior Speaker: Cameron Rudd, University of Illinois Date: Apr 26, 2022 Time: 3:00 PM Zoom info below Abstract: The topology of a knot is intimately related to that of its exterior, which is the complement of an open regular neighborhood of the knot. Knots are typically encoded by planar diagrams, whereas their exteriors, which are compact 3-manifolds with torus boundary, are encoded by triangulations. I will discuss a practical algorithm for finding a diagram of a knot given a triangulation of its exterior. Our method applies to links as well as knots, and allows us to recover links with hundreds of crossings. This is joint work with Nathan Dunfield and Malik Obeidin. Zoom info: https://zoom.us/j/94529451960?pwd=ekkxYUsrRGt5bVdEQWJRN0JOZ04wZz09 Meeting ID: 945 2945 1960 Passcode: JSJDecomp ______________________ Neil R. Hoffman Assistant Professor Department of Mathematics 523 Math Science Building Oklahoma State University Stillwater, OK 74078-1058 405-744-7791 http://math.okstate.edu/people/nhoffman

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Today in Topology - Clément Maria
by Hoffman, Neil 19 Apr '22

19 Apr '22

Hello everyone, Today we have our penultimate speaker of the spring Clément Maria. Title: Parameterized complexity in low dimensional topology Speaker: Clément Maria, Inria Date: Apr 19, 2022 Time: 3:00 PM Abstract: Parameterized complexity is a theory allowing a finer analysis of the complexity of algorithms, which was originally applied to graph problems. In this talk, I will survey recent results on the use of parameters for algorithmic and combinatorial topology, with a focus on knots and 3-manifolds. I will try to motivate and highlight the particular flavor of parameterized complexity when applied to the computation of quantum invariants, at the interface of topology, classical and quantum computational complexity, and combinatorics Zoom Info: https://zoom.us/j/94529451960?pwd=ekkxYUsrRGt5bVdEQWJRN0JOZ04wZz09 Meeting ID: 945 2945 1960 Passcode: JSJDecomp Join by Skype for Business https://zoom.us/skype/94529451960 [https://st3.zoom.us/static/6.1.6008/image/thumb.png]<https://zoom.us/skype/94529451960> Join our Cloud HD Video Meeting<https://zoom.us/skype/94529451960> Zoom is the leader in modern enterprise video communications, with an easy, reliable cloud platform for video and audio conferencing, chat, and webinars across mobile, desktop, and room systems. Zoom Rooms is the original software-based conference room solution used around the world in board, conference, huddle, and training rooms, as well as executive offices and classrooms. Founded in 2011, Zoom helps businesses and organizations bring their teams together in a frictionless environment to get more done. Zoom is a publicly traded company headquartered in San Jose, CA. zoom.us ______________________ Neil R. Hoffman Assistant Professor Department of Mathematics 523 Math Science Building Oklahoma State University Stillwater, OK 74078-1058 405-744-7791 http://math.okstate.edu/people/nhoffman

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Tomorrow (Tuesday) in Topology seminar
by Hoffman, Neil 04 Apr '22

04 Apr '22

Hello everyone, Tomorrow we will have Chaeryn Lee joining us from UIUC. Her title and abstract are below: Essential Surfaces in the Exterior of K13n586 Speaker: Chaeryn Lee, University of Illinois Date: Apr 5, 2022 Time: 3:00 PM Room: Virtual (see below) Abstract: We count the number of isotopy classes of closed, connected, orientable, essential surfaces embedded in the exterior B of the knot K13n586. The main result is that the count of surfaces by genus is equal to the Euler totient function. This is the first manifold for which we know the number of surfaces for any genus. The main argument is to show when normal surfaces in B are connected by counting their number of components. We implement tools from Agol, Hass and Thurston to convert the problem of counting components of surfaces into counting the number of orbits in a set of integers under a collection of bijections defined on its subsets. In this talk we will focus on understanding these techniques from Agol, Hass and Thurston and how they are applied to the specific case of our knot exterior. Topic: Okstate Topology Seminar Time: This is a recurring meeting Meet anytime Join Zoom Meeting https://zoom.us/j/94529451960?pwd=ekkxYUsrRGt5bVdEQWJRN0JOZ04wZz09 Meeting ID: 945 2945 1960 Passcode: JSJDecomp Join by Skype for Business https://zoom.us/skype/94529451960 ______________________ Neil R. Hoffman Assistant Professor Department of Mathematics 523 Math Science Building Oklahoma State University Stillwater, OK 74078-1058 405-744-7791 http://math.okstate.edu/people/nhoffman

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Today in topology seminar
by Hoffman, Neil 29 Mar '22

29 Mar '22

Hello everyone, Today in seminar we have Rafał Siejakowski zooming in from São Paulo. The details are below. Title Meromorphic 3D-index and its asymptotics Speaker: Rafał Siejakowski, University of São Paulo Date: Mar 29, 2022 Time: 3:00 PM Room: https://zoom.us/j/94529451960?pwd=ekkxYUsrRGt5bVdEQWJRN0JOZ04wZz09 Abstract: The meromorphic 3D-index is a new and somewhat mysterious topological invariant of orientable 3-manifolds with toroidal boundary, defined as a state integral of Turaev– Viro type on ideal triangulations. The ”states” in this integral are formal assignments of circle-valued dihedral angles to the edges of the tetrahedra. In this talk, we explain the predicted asymptotic behaviour of this invariant when the quantisation parameter q tends to 1. Conjecturally, our asymptotic limit contains ”classical” information about certain flat PSL(2,C)-bundles on the manifold, including the hyperbolic volume and adjoint Reidemeister torsion whenever the manifold admits a complete hyperbolic structure of finite volume. Topic: Okstate Topology Seminar Time: This is a recurring meeting Meet anytime Join Zoom Meeting https://zoom.us/j/94529451960?pwd=ekkxYUsrRGt5bVdEQWJRN0JOZ04wZz09 Meeting ID: 945 2945 1960 Passcode: JSJDecomp Join by Skype for Business https://zoom.us/skype/94529451960 [https://st3.zoom.us/static/6.0.5598/image/thumb.png]<https://zoom.us/skype/94529451960> Join our Cloud HD Video Meeting<https://zoom.us/skype/94529451960> Zoom is the leader in modern enterprise video communications, with an easy, reliable cloud platform for video and audio conferencing, chat, and webinars across mobile, desktop, and room systems. Zoom Rooms is the original software-based conference room solution used around the world in board, conference, huddle, and training rooms, as well as executive offices and classrooms. Founded in 2011, Zoom helps businesses and organizations bring their teams together in a frictionless environment to get more done. Zoom is a publicly traded company headquartered in San Jose, CA. zoom.us ______________________ Neil R. Hoffman Assistant Professor Department of Mathematics 523 Math Science Building Oklahoma State University Stillwater, OK 74078-1058 405-744-7791 http://math.okstate.edu/people/nhoffman

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Tomorrow (Tuesday) in Topology seminar
by Hoffman, Neil 21 Mar '22

21 Mar '22

Hello everyone, Tomorrow we will have Kristof Huszar joining us. He will be joining us from France, so we are especially grateful about his flexibility when determining his speaking hours. Title On quantifying the width of 3-dimensional manifolds Speaker: Kristóf Huszár, Inria Date: Mar 22, 2022 Time: 3:00 PM central (9pm CET) Room: https://zoom.us/j/94529451960?pwd=ekkxYUsrRGt5bVdEQWJRN0JOZ04wZz09 Abstract: There are various ways of defining the ”width” of a 3-dimensional manifold. Well-known examples include the Heegaard genus, or, in case of hyperbolic 3-manifolds, the volume. Driven by the algorithmic study of 3-manifolds, recent years have seen a growing interest in combinatorial notions of width defined through triangulations: it has been shown that several computationally hard problems about 3-manifolds can be efficiently solved for triangulations that are sufficiently ”thin” in a certain sense. In this talk we give an overview of recent results that link these combinatorial width parameters with classical topological invariants of 3-manifolds in a quantitative way. To establish our theorems, we rely on generalized Heegaard splittings and on layered triangulations. Joint work with Jonathan Spreer and Uli Wagner. Here is the full zoom info: Topic: Okstate Topology Seminar Time: This is a recurring meeting Meet anytime Join Zoom Meeting https://zoom.us/j/94529451960?pwd=ekkxYUsrRGt5bVdEQWJRN0JOZ04wZz09 Meeting ID: 945 2945 1960 Passcode: JSJDecomp Join by Skype for Business https://zoom.us/skype/94529451960 ______________________ Neil R. Hoffman Assistant Professor Department of Mathematics 523 Math Science Building Oklahoma State University Stillwater, OK 74078-1058 405-744-7791 http://math.okstate.edu/people/nhoffman

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Today in topology seminar
by Hoffman, Neil 21 Feb '22

21 Feb '22

Hello everyone, Today we are happy to have Joan Licata. Her title, abstract and the zoom link can be found below. Title: Diagrams for Three-Manifold Spines Speaker: Joan Licata, Australia National University/ICERM Date: Feb 22, 2022 Time: 3:00 PM Link: https://zoom.us/j/94529451960?pwd=ekkxYUsrRGt5bVdEQWJRN0JOZ04wZz09 Join our Cloud HD Video Meeting<https://zoom.us/j/94529451960?pwd=ekkxYUsrRGt5bVdEQWJRN0JOZ04wZz09> Zoom is the leader in modern enterprise video communications, with an easy, reliable cloud platform for video and audio conferencing, chat, and webinars across mobile, desktop, and room systems. Zoom Rooms is the original software-based conference room solution used around the world in board, conference, huddle, and training rooms, as well as executive offices and classrooms. Founded in 2011, Zoom helps businesses and organizations bring their teams together in a frictionless environment to get more done. Zoom is a publicly traded company headquartered in San Jose, CA. zoom.us Abstract: To study knots in R^3 , it’s natural to analyse the combinatorics of their projections to some plane. To generalise this to arbitrary three-manifolds, one can consider projections to spines, two-complexes which play an important role in computational topology. In addition to describing some results about spine projections of isotopic links, I’ll explain a connection to an open result about shadows of four-manifolds. The work I’ll describe is joint with Brand, Burton, Dancso, He, and Jackson. ______________________ Neil R. Hoffman Assistant Professor Department of Mathematics 523 Math Science Building Oklahoma State University Stillwater, OK 74078-1058 405-744-7791 http://math.okstate.edu/people/nhoffman

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Tomorrow in Topology seminar
by Hoffman, Neil 14 Feb '22

14 Feb '22

Hello everyone, You are receiving this email because you signed up for the topology list some time before now. If you would like to be left off the list let me know and I can do that for you. If not, then this week I will be speaking in seminar. The zoom link for my talk is (full zoom info is at the end of the email): https://zoom.us/j/94529451960?pwd=ekkxYUsrRGt5bVdEQWJRN0JOZ04wZz09 Title: Fully Augmented Link complements and Bianchi Groups Speaker: Neil Hoffman, Oklahoma State Date: Feb 15, 2022 Time: 3:00 PM Room: Virtual Abstract: A Bianchi group is $PSL(2,O_d)$ for some $O_d$, the ring of integers in a quadratic imaginary field. These are some of the first and most well-studied Kleinian groups. A fully augmented link (FAL) is a natural diagrammatic object and its complement tends to have nice geometric properties as well. Some of the simplest FAL complements also cover the quotients of $H^3$ by Bianchi groups. In some sense, both objects give standard examples in 3-manifold topology. Two natural questions are then: 1) which fully augmented link complements have this property? 2) which Bianchi groups contain a fully augmented link group? As part of joint work (in progress) with Will Worden, we can answer both of these questions save a few boundary cases. An interesting corollary of our work so far is that no FAL complement decomposes into regular ideal tetrahedra. Topic: Okstate Topology Seminar Time: This is a recurring meeting Meet anytime Join Zoom Meeting https://zoom.us/j/94529451960?pwd=ekkxYUsrRGt5bVdEQWJRN0JOZ04wZz09 Meeting ID: 945 2945 1960 Passcode: JSJDecomp Join by Skype for Business https://zoom.us/skype/94529451960 ______________________ Neil R. Hoffman Assistant Professor Department of Mathematics 523 Math Science Building Oklahoma State University Stillwater, OK 74078-1058 405-744-7791 http://math.okstate.edu/people/nhoffman

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Today in topology seminar
by Hoffman, Neil 16 Nov '21

16 Nov '21

Hello everyone, Today we have Chi Cheuk Tsang from UC-Berkeley. The title, abstract, and (usual) link are below: Join Zoom Meeting https://zoom.us/j/94529451960?pwd=ekkxYUsrRGt5bVdEQWJRN0JOZ04wZz09 Meeting ID: 945 2945 1960 Passcode: JSJDecomp Topology Seminar 3:00 PM Virtual meeting Markov partitions for geodesic flows Chi Cheuk Tsang, University of California at Berkeley Host: Neil Hoffman Abstract: Geodesic flows of negatively curved surfaces are one of the two classical families of Anosov flows on 3-manifolds. These are interesting objects to study, because, among other reasons, their periodic orbits are in one-to-one correspondence with the isotopy classes of closed curves of the surface. In this talk, we will start by introducing these geodesic flows, then explain the concept of Markov partitions, which is a useful tool for studying periodic orbits of Anosov flows in general. We will then illustrate a way of obtaining Markov partitions for these geodesic flows, via something called veering branched surfaces. ______________________ Neil R. Hoffman Assistant Professor Department of Mathematics 523 Math Science Building Oklahoma State University Stillwater, OK 74078-1058 405-744-7791 http://math.okstate.edu/people/nhoffman

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Today in Topology seminar (3pm Central, 4pm eastern)
by Hoffman, Neil 09 Nov '21

09 Nov '21

Dear Topologists, Today in seminar we have Allison Moore speaking. The zoom link is the same as usual: Topic: Okstate Topology Seminar Time: This is a recurring meeting Meet anytime Join Zoom Meeting https://zoom.us/j/94529451960?pwd=ekkxYUsrRGt5bVdEQWJRN0JOZ04wZz09 Meeting ID: 945 2945 1960 Passcode: JSJDecomp Her title and abstract are here: Title: Conway spheres and immersed curves Speaker: Allison Moore, Virginia Commonwealth University Date: Nov 9, 2021 Time: 3:00 PM (4PM eastern) Room: Virtual Abstract: A tangle decomposition along a Conway sphere breaks a knot or link into simpler pieces, each of which is a two-string tangle. In this talk, we’ll discuss how Heegaard Floer and Khovanov homologies can be approached and calculated using tangle decompositions. In both cases, the algebraic invariants can be realized geometrically as immersed curves on the four-punctured sphere. This strategy turns out to be quite useful for studying L-space knots and investigating two classic open problems: the cosmetic surgery conjecture and the cosmetic crossing conjecture. This is joint with Kotelskiy, Lidman, Watson and Zibrowius. ______________________ Neil R. Hoffman Assistant Professor Department of Mathematics 523 Math Science Building Oklahoma State University Stillwater, OK 74078-1058 405-744-7791 http://math.okstate.edu/people/nhoffman

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