Topological Graph Theory is one of the most interesting research areas in graph theory, related to Four Color Theorem, a celebrated theorem in the 20th century mathematics. Seiya Negami is a pioneer of the research area in Japan, and he started a workshop on topological graph theory at Yokohama National University in 1989, which was a small meeting with only five or six speakers. This was the 1st Workshop on Topological Graph Theory (TGT), and the origin of the long standing academic event in our university.

From 1989 to 2012, we have continued to organize TGT annually. They are almost domestic and many students presented their results there, but we had two memorial ones as international conference, which were the 10th in 1998 and 20th in 2008.

This year, we will have the 25th. So celebrating its continuation during a quarter century, we will have the memorial international workshop with six plenary speakers.

• Seiya Negami (Yokohama National University)
• Atsuhiro Nakamoto (Yokohama National University)
• Katsuhiro Ota (Keio University)
• Yusuke Suzuki (Niigata University)
• Jun Fujisawa (Keio University)
• Kenta Ozeki (National Institute of Informatics)