Editorial Conclusion for the Special Issue “Special Issue in Honor of the 60th Birthday of Professor Hong-Kun Xu”

Professor Dr. Hong-Kun Xu

Professor Hong-Kun Xu received his PhD degree from Xi’an Jiaotong University in 1988. He is currently a distinguished professor at Hangzhou Dianzi University, China. In 2004, he received the South African Mathematical Society Research Distinction Award and the Second Prize for Natural Science of the Ministry of Education of China. He is the former Head of the Department of Applied Mathematics and Dean of the College of Science at National Sun Yat-sen University, Taiwan. He was elected as a member of the Academy of Science of South Africa in 2005, and a fellow to the Academy of Sciences for the Developing World (TWAS) in 2012. He was also selected at the “Thousand Talents Program” of Zhejiang Province in 2014 and named as a Thomson Reuters/Clarivate Highly Cited Researcher from 2014 to 2018 and an Elsevier Chinese Highly Cited Researcher from 2019 to 2021. He has published approximately 250 research papers in journals and delivered academic speeches (invited/keynote/plenary) at more than 50 international academic conferences. He is serving on the editorial boards for more than 20 international mathematical journals. His main research interests include nonlinear functional analysis, optimization theory and algorithms, Banach space geometry theory, fixed point theory and applications, nonlinear mapping iteration method, inverse problem and its regularization method, financial mathematics, etc.

This Special Issue pays tribute to Professor Hong-Kun Xu’s significant contributions to these fields and provides some important recent advances in theory, methods, and applications. It comprises original and high-quality research papers that inspire advances in nonlinear analysis, optimization, and their applications. For more information, please visit the website: https://www.mdpi.com/journal/axioms/special_issues/hk_xu, accessed on 26 February 2021.

The Guest Editors have striven to ensure the success of this Special Issue, and we believe our efforts have been successful. The Guest Editors organized a comprehensive review process for each submission based on the journal’s policy and guidelines. We have received 44 submissions and, after a comprehensive review process, 16 high-quality works have been accepted for publication (with an acceptance rate of around 0.36). The accepted papers can be divided according to the following scheme considering their main purposes:

• Fixed point theory and applications (see [1,2,3,4,5]);
• Algorithms for nonlinear problems (see [1,3]);
• Nonlinear methods for ODEs and PDEs with applications (see [6,7,8,9]);
• Convex analysis and inequality theory (see [10,11,12,13]);
• Optimization (see [1,3,9,12,13,14]);
• Functional analysis (see [5,6,8,15,16]).

We hope that interested researchers and practitioners will be inspired by this Special Issue and find it valuable to their own research.

This Special Issue has highlighted important issues and raised several new problems in this research area. We would like to express our hearty thanks to the editorial team and the reviewers of Axioms, particularly the Editor-in-Chief Prof. Dr. Humberto Bustince and the Assistant Editor Luna Shen, for their invaluable support throughout the editing process.