Mdtop November 2021

mdtop@mathdept.okstate.edu

1 participants
3 discussions

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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Today in topology seminar 3pm central (1pm Pacific)
by Hoffman, Neil 02 Nov '21

02 Nov '21

Hello everyone, Today we have Kyle Miller from Berkeley. The link for his talk is: Join Zoom Meeting https://zoom.us/j/94529451960?pwd=ekkxYUsrRGt5bVdEQWJRN0JOZ04wZz09 Meeting ID: 945 2945 1960 Passcode: JSJDecomp His title and abstract are below: Title: The homological arrow polynomial Speaker: Kyle Miller, UC - Berkley Date: Nov 2, 2021 Time: 3:00 PM Room: Virtual Abstract: The Kauffman bracket is a Laurent polynomial invariant of framed unoriented links in the 3-sphere, and it can be calculated via locally defined skein relations. Applying these skein relations to links in other 3-manifolds yields invariants in the Kauffman bracket skein module, which is a relatively complicated object. I will talk about a relatively easy to compute multivariable Laurent polynomial invariant for links in thickened surfaces, obtained as a functional on the skein module, and how an evaluation of this invariant coincides with the arrow polynomial defined by Kauffman and Dye. This homological arrow polynomial is an invariant of virtual links (i.e., it is unchanged under destabilization along vertical annuli in the complement), and it has applications to checkerboard-colorability of virtual links, for example in completing Imabeppu’s characterization of checkerboard colorability of virtual knots with at most four crossings. ______________________ 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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Mdtop November 2021