On May 7, the second lecture of the 2021 "Famous Teachers' University Lecture Hall" hosted by the School of Mathematical Sciences and the Institute of Applied System Analysis of Jiangsu University opened smoothly in the cloud. The guest speaker invited in this issue is Professor Qing Han, a tenured professor of the Department of Mathematics of the University of Notre Dame, and an internationally renowned expert on nonlinear partial differential equations and geometric analysis. More than 80 teachers and students attended the lecture, including Professor Junping Shi from the College of William and Mary, Associate Professor Genggeng Huang from Fudan University, Professor Chunpeng Wang from Jilin University, Professor Shibo Liu from Xiamen University, Professor Danping Ding and Professor Jun Wang from Jiangsu University.

Before the lecture, Dean Zhang Zhitao of the Academy of Mathematics briefly introduced Professor Han Qing and presided over the lecture.

Professor Han Qing gave a wonderful academic report on the topic of "Geodesics and isometric immersions in Kirigami". He first played a computer simulation experiment video of paper-cutting. The experiment reflected the process of paper-cutting changing shape during the pulling process. Then, from this simple demonstration, an important mathematical conjecture is derived-making the image of the geodesic connecting any two points in the three-dimensional space the existence of straight line segments and equidistant embedding, and introduced his understanding of the conjecture and the latest research. Professor Han’s report is easy to understand, and demonstrates his profound mathematical skills by showing the profound connection between simple phenomena in daily life and important geometric problems in mathematics. Under his vivid explanation, the participating teachers and students had a certain understanding of the knowledge in this field, which increased their own knowledge reserves. After the report, Professor Han and everyone had an in-depth discussion on related academic issues, and answered the questions that teachers and students were concerned about.

Finally, Dean Zhang Zhitao made a concluding speech on the lecture.