Abstract
In 2019 Xuding Zhu, Professor and Director of Center for Discrete Mathematics at Zhejiang Normal University, China, had a personal anniversary. On this occasion National Sun Yat-sen University in Kaoshung (together with Institute of Mathematics, Academia Sinica, Ministry of Science and Technology and Mathematics Research Promotion Center) organized on June 17-21, 2019, an International Conference on Graph Theory, Combinatorics and Applications.
Already before the meeting it had been suggested to organize a special issue of a good journal which would reflect the many fold personality and achievements of Xuding Zhu. We enthusiastically followed this idea and were only pleased by an overwhelming positive response from our colleagues.
This is then the result which we believe is a very nice tribute to Xuding's excellent work and longstanding activity.