Yat-Sen Wong
王逸晨

Department of Mathematics
University of Illinois at Urbana-Champaign
273 Altgeld Hall, MC-382
1409 W Green Street
Urbana, Illinois 61801-2975

Email: wong65 AT illinois DOT edu
Office: Altgeld Hall 155

 

About Me:

I am a third year Ph.D. student in the department of Mathematics at the University of Illinois at Urbana-Champaign.
I was borned in Shanghai and grow up in Hong Kong.
Before I come to US, I finished my undergraduate and master degree in Mathematics at The Chinese University of Hong Kong.

Research Interests:

My research interest is symplectic geometry and I am currently working on problems about symplectic embeddings and J-holomorphic curves.

Publications and Preprints:

  1. Yat-Sen Wong, Whitney's embedding theorem for pseudo-holomorphic discs, Illinois J. Math. (special issue dedicated to John D'Angelo), to appear
  2. Yat-Sen Wong, Symplectic embedding of real bi-disc, Complex Variables and Elliptic Equations, DOI:10.1080/17476933.2011.605448
  3. R. F. Barret, T. Chan, E. F. D'Azevedo, E. F. Jaeger, K. Wong and R. Wong, Complex version of high performance computing LINPACK benchmark (HPL), Concurrency Computat.: Pract. Exper. 2000; 00:1-7

Education:

2009 -  ?   Ph.D. in Mathematics, University of Illinois at Urbana-Champaign. 2007 - 2009 Master of Philosophy in Mathematics, The Chinese University of Hong Kong.
Advisor: Professor Hing Sun Luk. 2003 - 2006 Bachelor of Science in Mathematics, The Chinese University of Hong Kong.

Teaching:

I am currently teaching one discussion section (ED3) of MATH 231 EL1, Calculus II.
Click here for the solutions of quizzes in my class.

Here is a list of my past teaching duties:
University of Illinois at Urbana-Champaign (UIUC):
Fall 2011 MATH 241 Calculus III discussion section
Spring 2011, Fall 2010, Spring 2010 Math 231 Calculus II discussion section
Fall 2009 Grading jobs

The Chinese University of Hong Kong:
Spring 2009 Tutorial classes (similar to discussion sections in UIUC) for MAT4210 Financial Mathematics
Fall 2008 Tutorial classes for MAT2310 Linear Algebra & Applications
Summer 2008 Tutorial classes for MAT3280 Introductory Probability
Spring 2008 Tutorial classes for MAT4210 Financial Mathematics
Fall 2007 Tutorial classes for MAT2310 Linear Algebra & Applications

I am in the "list of teachers ranked as excellent by their students" for Spring 2011

Besides those teaching experiences listed above, I also served as a head TA in Enrichment Programme for Young Mathematics Talents during summer 2010.

 

Interesting Mathematics: Turning a sphere "inside-out"

Let $f:S^2\rightarrow\mathbb{R}^3$ be the standard embedding of a 2-sphere into the 3-dimensional Euclidean space, Stephen Smale (1958) proved that $f$ and $-f$ are regularly homotopic. (This means if we view $f$ and $-f$ as immersions from $S^2$ into $\mathbb{R}^3$, then they are homotopic through immersions and the homotopy extends continuously to a homotopy of the tangent bundles.) Smale prove the theorem by considering the homotopy group of the Stiefel manifold and showing that the homotopic group of immersions from 2-sphere to Euclidean 3-space vanishes, hence $f$ and $-f$ are regularly homotopic.

People notice that Smale's proof did not produce any explicit regular homotopy that turns the sphere inside out, therefore the question remains is to give such an explicit regular homotopy. This problem is solved after many years by several models like "half-way models" and "minimax eversions". Aside from the real models, there are many digital videos clearly explain how to turn the sphere inside out, for example:

"Sphere Inside out Part-I"
"Sphere Inside out Part-II"
"The Optiverse"