Mdtop

mdtop@mathdept.okstate.edu

247 discussions

This week in topology
by Hoffman, Neil 18 Feb '20

18 Feb '20

Sorry for the late notice here: This week Robert will be speaking. Title: Finding knot diagrams is hard Speaker: Robert Haraway, Oklahoma State Date: Feb 18, 2020 Time: 3:30 PM Room: MSCS 509 Abstract: I will discuss the challenge of finding a diagram of a knot given a triangulation of the complement. ______________________ 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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Seminar Today
by Hoffman, Neil 11 Feb '20

11 Feb '20

Hello Everyone, We have Martin Bobb visiting today from UT. His title and abstract are below: Title: Flats in compact convex projective manifolds Speaker: Date: Time: Room: Martin Bobb, University of Texas Feb 11, 2020 3:30 PM MSCS 509 Abstract: Convex projective structures on manifolds are a rich generalization of hyperbolic structures. One key difference is that a convex projective manifold may have flat substruc- tures. We will discuss some first examples of convex projective geometry, and then describe a natural decomposition of compact convex manifolds along their codimension-1 flats. This generalizes a result of Benoist, which states that a compact convex projective 3-manifold geometrically JSJ-decomposes into cusped hyperbolic manifolds. ______________________ 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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Seminar today. Seminar cancelled next week
by Hoffman, Neil 28 Jan '20

28 Jan '20

Hello everyone, First a few pieces of business. If you haven't registered for redbud and are interested in going. Please register soon: Website: https://mattclay.hosted.uark.edu/Redbud/spring2020.html Registration: https://docs.google.com/forms/d/e/1FAIpQLSfohB4bR8uNzEuySo5UywYzRoU4r_Czcrq… Also, if anyone is heading out Friday mid-day let me know. Will Worden is coming to visit that week and might hitch an early ride to redbud. There is also funding for graduate students to speak at a topology conference in Eastern Illinois. https://ux1.eiu.edu/~gdt/2020.html Third, David Wright is speaking about packings of hyperbolic space in number theory seminar. Forth, our speaker for next week is not coming due to corona virus. Pengcheng expresses his apologies. Finally, today I am speaking in seminar. My title and abstract are below: Cusp types covered by hyperbolic knot complements Speaker: Neil Hoffman, Oklahoma State Date: Jan 28, 2020 Time: 3:30 PM Room: MSCS 509 Abstract: Let Q be an orbifold quotient of a hyperbolic knot complement. This talk will give a complete classification of the types of cusps Q can admit. In particular, we will show that Q does not have a S 2 (2, 4, 4) cusp. We will also discuss the non-orientable case and the connection between this problem and the question of which knots admit hidden symmetries. 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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3:30 organizational meeting
by Hoffman, Neil 14 Jan '20

14 Jan '20

See you there. ______________________ 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 Double Header
by Hoffman, Neil 03 Dec '19

03 Dec '19

Hello everyone, I hope you like efficient triangulations! We have two talks about them on tap today. First, Bus will be speaking at 2:30 in MSCS 405 and then Birch will be speaking in MSCS 509 at 3:30. Their titles and abstracts are below. Title: Efficient Triangulations of 3-manifolds Speaker: Bus Jaco, Oklahoma State Date: Dec 3, 2019 Time: 2:30 PM Room: MSCS 405 Abstract: We will define and discuss efficient triangulations of 3-manifolds and show that efficient triangulations of cusped 3-manifolds lift to efficient triangulations for any inflation. In particular, if a triangulation of a cusped 3-manifold is 1-efficient, then any inflation of that triangulation is 1–efficient. These results will be used in Birch’s talk on December 3. Title: 1-efficient Triangulated Dehn Filling Speaker: Birch Bryant, Oklahoma State Date: Dec 3, 2019 Time: 3:30 PM Room: MSCS 514 Abstract: By combining algorithms developed separately by Lackenby and Jaco, we provide an algorithm to construct 1-efficient triangulations for all but at most finitely many possible Dehn fillings of a specified triangulated knot manifold. This relies heavily notion of triangulated Dehn fillings developed by Jaco to have control over the normal surfaces added during the filling. After discussing some relevant background, I will describe how this method works and what triangulations it can be applied to. ______________________ 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 Postponed
by Hoffman, Neil 25 Nov '19

25 Nov '19

Hello everyone, Sorry for the short notice. Today's seminar has been postponed until December 3 at 2:30. It will be followed by a seminar by Birch at 3:30 so mark your calendars for that day. 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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Today in Seminar
by Hoffman, Neil 25 Nov '19

25 Nov '19

Hello everyone, Today we have Bus speaking at 3:30 in MSCS 514 (not the usual room). Title:Efficient Triangulations of 3-manifolds Abstract: We will define and discuss efficient triangulations of 3-manifolds and show that efficient triangulations of cusped 3-manifolds lift to efficient triangulations for any inflation. In particular, if a triangulation of a cusped 3-manifold is 1-efficient, then any inflation of that triangulation is 1–efficient. These results will be used in Birch’s talk on December 3. ______________________ 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 events this week
by Hoffman, Neil 19 Nov '19

19 Nov '19

Hello everyone, Today there is no topology seminar. Bus was kind enough to reschedule his talk for next Monday at 3:30 because he has to receive a(nother) award at CAS Convocation today. Dr. Jay Schweig is also receiving an award for his outstanding teaching. I will send out more information about Bus's talk next week. We do have an organizational meeting for this Saturday's redbud conference. At this stage, things are more or less set, so there are just minor logistics to work out. However, anyone interested in helping out should meet in Robert's office at 4:30 for a short meeting. This Saturday we have our fall meeting of the Redbud topology conference in MSCS 514. http://math.okstate.edu/conferences/redbud/ Monday: Bus will be speaking at 3:30 in MSCS 514. ______________________ 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 Junior topology
by Hoffman, Neil 12 Nov '19

12 Nov '19

Hello everyone, Today we have Dave Futer speaking in the seminar: He will be speaking on some cool stuff and his title and abstract are below: Title: Systoles and cosmetic surgeries Abstract: A pair of distinct slopes for a knot K is called a cosmetic surgery pair if the Dehn surgeries along those slopes yield the same oriented 3-manifold. Gordon conjectured that such pairs do not exist. I will describe a theorem that says any potential cosmetic surgery pairs on a hyperbolic knot K belong to a finite list of slopes, whose size is determined by the systole (shortest closed geodesic) in the complement of K. For a typical knot, this list has no more than 10 pairs of slopes. This makes it feasible to check the remaining pairs by computer and prove that K has no cosmetic surgeries at all. For instance, prime knots up to 15 crossings have no cosmetic surgeries. This is joint work with Jessica Purcell and Saul Schleimer. ______________________ 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 Semianr
by Hoffman, Neil 15 Oct '19

15 Oct '19

I am speaking. My title and abstract are below: Title: Three sphere recognition modulo GRH Speaker: Neil Hoffman Date: Oct 15, 2019 Time: 3:30 PM Room: MSCS 509 Abstract: In this largely expository talk, I will discuss the interplay between the Generalized Riemann Hypothesis and the problem of producing a relatively small sized certificate that a 3-manifold is not the three sphere. ______________________ 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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