*Guangzhou Discrete Mathematics Seminar* is a seminar series which covers all aspects of discrete mathematics, and started at Sun Yat-sen University, Guangzhou, China, in Fall 2017. The seminars take place frequently during term time - approximately once every two weeks, at School of Mathematics, Sun Yat-sen University. The usual meeting room and day of the week for the seminars are generally fixed for a particular semester, but these are expected to vary from one semester to another.
The seminars aim to promote the presence of discrete mathematics in Guangzhou, as well as to strengthen the discrete mathematics community there.
Everyone is welcome to attend. If anyone is interested in giving a seminar talk, or for general enquiries, please contact one of the organisers.

**
Organisers
**

Ping Hu: huping9@mail.sysu.edu.cn

Henry Liu: liaozhx5@mail.sysu.edu.cn

Chao Yang: yangchao@gdufs.edu.cn

Zanbo Zhang: eltonzhang2001@gmail.com

How to get to School of Mathematics, Sun Yat-sen University

###
Upcoming talks

**
2020.2
**
TBA

### Past talks

**
2020.1
**
7 January 2020 (Tuesday), 3-4pm, ***room 519***

**Jiaao Li (Nankai University, Tianjin, China)** *From map coloring to nowhere-zero flows* Poster

Planar graphs are vertex 4-colorable, and even 3-colorable if triangle-free. These results are known as 4CT and Grötzsch’s 3CT. Is there a better coloring for planar graphs with larger girth? A conjecture of Jaeger states that planar graphs of girth 2*k* are circular (2+2/*k*)-colorable, where the cases *k*=1,2 correspond to 4CT and 3CT. We provide partial results for the open cases *k*=4,6 and for the more general dual setting of nowhere-zero flows. Dually, Tutte’s and Jaeger’s flow conjectures predict existence of flows for highly connected graphs, and Lovász, Thomassen, Wu and Zhang (2013) showed that every 6*p*-edge-connected graph admits a circular (2+1/*p*)-flow. In this talk, we obtain circular (2+2/(2*p*-1))-flow and (< 2+1/*p*)-flow for (6*p*-2)- and (6*p*+2)-edge-connected graphs, respectively.

### Archive

Talks in 2017 2018 2019