Mdtop

mdtop@mathdept.okstate.edu

247 discussions

Tomorrow in topology seminar
by Hoffman, Neil 15 Sep '20

15 Sep '20

Tomorrow we have Josh Howie "coming" to speak at 3:45 central. The meeting link will be https://meet.google.com/frv-bgow-byi His title and abstract are below: Alternating genera of torus knots Speaker: Josh Howie, UC Davis Date: Sep 16, 2020 Time: 3:45 PM Room: https://meet.google.com/frv-bgow-byi Abstract: The alternating genus of a knot is the minimum genus of a surface onto which the knot has an alternating diagram satisfying certain conditions. Very little is currently known about this knot invariant. We study spanning surfaces for knots and define an alternating distance from the extremal spanning surfaces. This gives a lower bound on the alternating genus and can be calculated exactly for torus knots. We prove that the alternating genus can be arbitrarily large, find the first examples of knots where the alternating genus is exactly 3, and classify all toroidally alternating torus knots. ______________________ 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

1 0

Topology seminar at 3:45 today!
by Hoffman, Neil 09 Sep '20

09 Sep '20

Hello everyone, Today's seminar will use the same link as last week: meet.google.com/bqo-wbtp-gzj Thomas Kindred from University of Nebraska will be joining us. His title and abstract are below: A geometric proof of the flyping theorem Speaker: Thomas Kindred, University of Nebraska Date: Sep 9, 2020 Time: 3:45 PM Room: Virtual meeting Abstract: In 1898, Tait asserted several properties of alternating knot diagrams. These assertions came to be known as Tait’s conjectures and remained open through the discovery of the Jones polynomial in 1985. The new polynomial invariants soon led to proofs of all of Tait’s conjectures, culminating in 1993 with Menasco-Thistlethwaite’s proof of Tait’s flyping conjecture. In 2017, Greene gave the first geometric proof of part of Tait’s conjectures, while also answering a longstanding question of Fox by characterizing alternating links geometrically; Howie independently answered Fox’s question with a related characterization. I will use these new characterizations, among other techniques, to give the first entirely geometric proof of Menasco-Thistlethwaite’s Flyping Theorem. ______________________ 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

1 0

Topology Seminar, 3:45-4:45, Wednesday Sept 2
by Henry Segerman 01 Sep '20

01 Sep '20

Hi all, I will be speaking this week. ***Note the new Google Meet link:*** meet.google.com/bqo-wbtp-gzj Title: From veering triangulations to Cannon-Thurston maps Abstract: Agol introduced veering triangulations of mapping tori, whose combinatorics are canonically associated to the pseudo-Anosov monodromy. In previous work, Hodgson, Rubinstein, Tillmann and I found examples of veering triangulations that are not layered and therefore do not come from Agol’s construction. However, non-layered veering triangulations retain many of the good properties enjoyed by mapping tori. For example, Schleimer and I constructed a canonical circular ordering of the cusps of the universal cover of a veering triangulation. Its order completion gives the veering circle; collapsing a pair of canonically defined laminations gives a surjection onto the veering sphere. In work in progress, Manning, Schleimer, and I prove that the veering sphere is the Bowditch boundary of the manifold’s fundamental group. As an application we produce Cannon-Thurston maps for all veering triangulations. This gives the first examples of Cannon-Thurston maps that do not come, even virtually, from surface subgroups.

1 0

Test email
by Henry Segerman 30 Aug '20

30 Aug '20

Please ignore!

1 0

Today in Topology
by Hoffman, Neil 26 Aug '20

26 Aug '20

Hello everyone, Today I will be speaking. We will use google meet for the meeting: https://meet.google.com/frv-bgow-byi Here is my title, abstract, and other info: Title: Infinitely many geometric triangulations in a cover of every cusped 3-manifold Speaker: Me Date: Aug 26, 2020 Time: 3:45 PM Room: Virtual meeting Abstract: A triangulation T of a cusped hyperbolic 3-manifold is geometric if admits a fundamental domain which decomposes into convex ideal tetrahedra with positive angles. It is an open question as to whether every hyperbolic 3–manifold admits a single geometric triangulation. A follow-up question is how many geometric triangulations can one manifold admit? Dadd and Duan showed that some manifolds admit infinitely many geometric triangulations. And Luo, Schleimer and Tillmann showed that every manifold has a cover admitting at least one geometric triangulation. We prove that every cusped hyperbolic 3– manifold has a finite cover admitting infinitely many geometric ideal triangulations. This cover is constructed in several stages, using tools developed by Gueritaud, Luo, Schleimer, and Tillmann. The geometric ideal triangulations that we produce can be organized into an infinite binary tree of Pachner moves. This is joint work with Dave Futer. ______________________ 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

1 0

Possible time change
by Hoffman, Neil 18 Aug '20

18 Aug '20

Hello everyone, Thanks to everyone getting back to me on seminar. I wanted to ask if anyone has a conflict from 3:45-4:45 on Wednesdays for this semester. And then we can go back to Tuesdays at 3:30 next semester. It is easier to move the seminar time this semester because don't need to worry about room reservations. Please let me know if you are interested in coming to seminar but won't be able to make Wednesdays from 3:45-4:45. ______________________ 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

1 0

Organizational meeting today
by Hoffman, Neil 18 Aug '20

18 Aug '20

Hello everyone, We'll have the topology seminar organizational meeting today. We try using google meet: Here is the link. It should open up at 3:25pm today (central time). meet.google.com/vht-gefi-xex 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

1 0

Online Seminar at Warwick
by Hoffman, Neil 04 May '20

04 May '20

Hello topologists, I wanted to pass along information about a topology seminar going at Warwick. Many thanks to Saul Schleimer (who has many fine attributes including being a collaborator of Henry's) for setting this up: http://homepages.warwick.ac.uk/~masgar/Seminar/current_seminar.html The current conversion is that 16:00 UK time is 10 am our time. This week the seminar features Nathan Dunfield and Pryam Patel. Although many of you may have seen Nathan's talk at Redbud, I would still encourage you to attend because it might pay to be familiar to the beats of an online seminar. 1) I anticipate at least some of our seminar next year will be online, and 2) if you are on the job market next year, you may want to develop instincts for what makes an effective online presentation. 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

1 0

Topology seminar today
by Hoffman, Neil 05 Mar '20

05 Mar '20

Hello everyone, Will worden is stopping by OSU today before his talk in Fayetteville this weekend. He will be speaking in 509 at 2:30 on The Thurston norm ball via spun normal 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

1 0

Eric Towers speaking today
by Hoffman, Neil 25 Feb '20

25 Feb '20

Hello everyone, Eric Towers is speaking in topology seminar today. He will be discussing his own work. His title and abstract are below: Title:Building censuses of links in lens spaces Speaker: Eric Towers, Oklahoma State Date: Feb 25, 2020 Time: 3:30 PM Room: MSCS 509 Abstract: The theory and automation of the exhaustive study of links (including knots) in ^3 is understood. Extending these methods to completely enumerate links in specified ambient spaces other than S^3 is less well understood. For any fixed lens space L(p, q), we describe a method for producing all links with a prescribed complexity in the ambient L(p, q). We demonstrate progress in software to automate the enumeration and feature extraction of lens space link complements and their fillings. ______________________ 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

1 0

← Newer
1
...
4
5
6
7
8
9
10
...
25
Older →

Jump to page:

2025

2024

2023

2022

2021

2020

2019

2018

2017

2016

2015

2014

2013

2012

Mdtop