Mdtop

mdtop@mathdept.okstate.edu

247 discussions

Seminar this afternoon
by Jesse Johnson 04 Apr '13

04 Apr '13

Dear Topologists and Friends of Topology: Trent will give the topology seminar this afternoon at 3:30 in MSCS 514. Sorry for the late notice - I just posted this on announce and in the lounge yesterday. Also, because of the MAA meeting tomorrow, I'm not sure if the reading group should still meet at the usual time. If you've been attending the group, but there is an MAA event you plan to attend instead tomorrow, let me know. If there are enough people planning to miss it, I will send an e-mail to cancel the reading group meeting. (If you DON'T hear from me, we will still meet Friday afternoon at 2:30.) Title: High Distance Free Decompositions Abstract: Free decompositions were introduced by Kobayashi about a decade or so ago to construct pairs of knots whose tunnel number degenerates under connected sum. I inject some curve complex juices into them to construct knots with "High Distance Free Decompositions." Such knots have many interesting properties relating to their Heegaard structure, dehn surgery, and yes, the behavior of tunnel number under connected sum. This is joint work with Jesse.

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No Topology Seminar today
by Jesse Johnson 07 Mar '13

07 Mar '13

Dear Topologists and Friends of Topology, There will be no topology seminar this week due to the Redbud conference at UArk this weekend. For those of you in the reading group, we will also skip this week's meeting for the same reason. Jesse

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Seminar this afternoon
by Jesse Johnson 28 Feb '13

28 Feb '13

Dear Topologists and Friends of Topology, Bus will give the seminar talk this afternoon at 3:30 in MSCS 514. Title: Minimal Triangulations of 3-manifolds Abstract: The complexity of a 3-manifold M, denoted C(M), is the minimal number of tetrahedra necessary to triangulate M. We discuss the problem of determining the complexity of a 3-manifold and provide the complexities for certain infinite families of 3-manifolds. These are the only known infinite families of complexities. We will outline a proof in a rather approachable case by showing that the complexity of the product of a surface having genus g and the unit interval is 10g-4.

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Redbud in a week and a half.
by Jesse Johnson 27 Feb '13

27 Feb '13

Dear Topologists and Friends of Topology, This is a reminder that the Spring 2013 Redbud conference is the weekend after next (March 9-10) at the University of Arkansas. The conference website is http://math.uark.edu/6730.php If you are planning to attend, make sure to register ASAP (if you haven't already) and let me know if you don't have a ride yet. Jesse

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Seminar this afternoon
by Jesse Johnson 21 Feb '13

21 Feb '13

Dear Topologists and Friends of Topology, Weiping will give the seminar talk this afternoon at 3:30 in MSCS 514. Title: K-stablility and K\"{a}hler-Einstein metrics after Gang Tian Abstract: In this talk, we present the recent work of G. Tian on the proof of the Yau-Tian-Donaldson conjecture. {\bf Theorem (Tian 2012)} Let $M$ be a Fano manifold canonically polarized by the anti-canonical bundle $K_M^{-1}$. If $M$ is K-stable, then it admits a K\"{a}hler-Einstein metric.

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Seminar today
by Jesse Johnson 14 Feb '13

14 Feb '13

Dear Topologists and Friends of Topology: I'll be the speaker for the topology seminar this afternoon at 3:30 in MSCS 514. Title: Constructing geodesics in the curve complex Abstract: The curve complex for a surface is a simplicial complex whose vertices represent simple closed curves in the surface. The large scale geometry of the curve complex has proved to be closely related to both two-dimensional geometry (such as Teichmuller theory) and three-dimensional topology (such as Heegaard splittings). I will give an introduction to the structure of this complex, describe a construction that produces geodesics in the complex, and (if time permits) describe some applications to three-dimensional topology.

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Seminar tomorrow
by Jesse Johnson 06 Feb '13

06 Feb '13

Dear Topologists and Friends of Topology, Elena will give the topology seminar tomorrow (Thursday). Title: Oriented matroids and straight-edge embeddings of graphs Abstract: Matroid theory is an abstract theory of dependence introduced by Whitney in 1935. It is a natural generalization of linear (in)dependence. Oriented matroids can be thought of as combinatorial abstractions of point configurations over the reals. To every linear (straight-edge) embedding of a graph one can associate an oriented matroid, and the oriented matroid captures enough information to determine which pairs of disjoint cycles in the embedded graph are linked. In this talk, we will introduce the basics of oriented matroids. Then we will discuss results about the type and number of links in linear embeddings of $K_9$, the complete graph on nine vertices, and in linear embeddings of the complete 3-partite graph $K_{3,3,1}$. This is joint work with Ramin Naimi.

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Seminar tomorrow
by Jesse Johnson 30 Jan '13

30 Jan '13

Sean will given the topology seminar this week, Thursday at 3:30 in 514. Title: Bridge number of knots obtained by twisting Abstract: Twisting along a curve (in a surface) or along an annulus (in a 3--manifold) is one way to obtain new knots from old. I'll discuss these operations with an eye towards how they affect the bridge number of the knots. Finally, I'll use a new theorem of Baker-Gordon-Luecke to answer several questions from my talk last semester.

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CBMS Notes
by Jesse Johnson 25 Jan '13

25 Jan '13

Wise - LectureNotesCBMS.pdf<https://docs.google.com/file/d/0BxG6UbtygwrUOVl6eS1hVEJNdWc/edit> I managed to track down a copy of the CBMS notes and they are attached to this e-mail. Jesse

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VHC Reading group
by Jesse Johnson 25 Jan '13

25 Jan '13

The first meeting of the VHC reading group will be this afternoon at 2:30 in MSCS 405. (Sorry I'm sending this to everyone on the mdtop list: I didn't take attendance after the seminar yesterday!) I am still trying to track down a PDF copy of Dani Wise's CBMS lecture notes on cube complexes, but you can find a very rough outline of his approach here: http://ldtopology.wordpress.com/2012/03/06/wises-conjecture/ You may also want to look at Ian Agol's preprint on the arXiv http://front.math.ucdavis.edu/1204.2810 and the paper by Bergeron and Wise that started it all http://front.math.ucdavis.edu/0908.3609 Jesse

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