GTA Seminar: Tillmann -- Normal Surfaces in 3-Manifolds: Algorithms, Experiments and Questions Discrete Uniformization Theorem for Polyhedral Surfaces

The original talk by Professor Feng Luo is cancelled due to visa reason. 
Sorry for any inconvenience. 

However, we have the following talk offered by Stephan Tillmann. It is 
supposed to warm up people for the incoming workshop in Week 5.  

Time: Tuesday, March 18, 12NOON--1PM. 

Room: Carslaw 535A. 

Title: Normal Surfaces in 3-Manifolds: Algorithms, Experiments and Questions

ABSTRACT: the theory of normal surfaces, introduced by Kneser in the 1920s 
and further developed by Haken in the 1960s plays a crucial role in 3-manifold 
topology. Normal surfaces allow topological problems to be translated into 
algebraic problems or linear programs, and they are the key to many important 
advances over the last $50$ years, including the solution of the unknot 
recognition problem by Haken, the 3-sphere recognition problem by Rubinstein 
and Thompson and the homeomorphism problem by Haken, Hemion and Matveev.

In this talk, I will summarise Haken's blueprint for algorithmic 3-manifold 
topology, discuss the "difficulty" of the computational problems from a 
theoretical and experimental perspective and state some open questions and 
challenges.

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Speaker: Prof. Feng Luo (Rutgers University)

http://www.math.rutgers.edu/~fluo/

Time: Tuesday, March 18, 12NOON--1PM. 

Room: Carslaw 535A. 

Lunch: seminar lunch is right after the talk at Law Annex Cafe, 
with reservation at 1:10PM. 

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Title: A Discrete Uniformization Theorem for Polyhedral Surfaces

ABSTRACT: we introduce a discrete conformality for polyhedral 
metrics on surfaces. It is shown that each polyhedral metric 
on a surface is discrete conformal to a constant curvature 
polyhedral metric which is unique up to scaling. Furthermore, 
the constant curvature metric can be found by a finite 
dimensional variational principle. This is a joint work with 
David Gu, Jian Sun and Tianqi Wu.

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Seminar website:

http://www.maths.usyd.edu.au/u/SemConf/Geometry/