February 2013 - Mdtop - mathdept.okstate.edu

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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