Preface

ᅟ

Professor Dr. Nguyen Khoa Son

This special issue of Vietnam Journal of Mathematics is dedicated to Professor Nguyen Khoa Son on the occasion of his 65th birthday. It consists of 18 invited papers contributed by the authors who have close academic ties to Nguyen Khoa Son. We would like to thank all the authors for their contributions.

Nguyen Khoa Son graduated from Karazin Kharcov National University, Ukraine, in 1972. In 1978, he received his candidate degree (PhD) in physico-mathematical sciences at the same university under the supervision of Valeri Korobov, and in 1990, he received the scientific degree doctor habil in mathematics at Institute of Mathematics in Warsaw, Polish Academy of Sciences, inspired by Czeslaw Olech.

From the university graduation until the retirement in 2013, Nguyen Khoa Son was affiliated as a research staff member of the Institute of Mathematics at Vietnam Academy of Science and Technology (VAST), where he has been assigned the title of full professor since 1996. At the same time, Son was also involved in many other scientific and management activities and held a number of leading positions in VAST: Deputy Director of the Institute of Mathematics (1995–1998), Director of Planning and Finance Department of VAST (1997–2001), Vice-President of VAST (2001–2008), and Editor-in-Chief of the Publishing House for Science and Technology (2006–2013).

The main research fields of Nguyen Khoa Son are optimization and mathematical control theory. He has obtained his most significant scientific results in the theory of controllability and stability of dynamical systems described by differential and difference equations as well as by differential inclusions. His results on local and global controllability of infinite-dimensional systems with constrained controls and their applications to different classes of dynamical systems, like the heat equations and the linear functional differential equations with positive controls, were among the earliest and most cited works in this research direction. In the last several decades, Son’s research interest was focused on robust analysis of controllability and stability of systems whose parameters are subjected to perturbations and uncertainties.

Nguyen Khoa Son has published around 80 scientific papers on the above topics, mostly in international mathematical journals, which have received an extensive record of citations. He has made also a significant contribution in mathematics education by supervising a number of PhD and master students.

In recognition of his scientific contributions, several honorable titles and awards have been assigned to Nguyen Khoa Son, such as Alexander-von-Humboldt Scholarship (1989–1990), Doctor Honoris Causa of the Karazin Kharkov National University (2004), Member of the Russian Academy of Natural Sciences (2008), and Vietnam Labor Medals of third rank (2002) and first rank (2009).

We would like to emphasize the great contribution made by Nguyen Khoa Son to the development of Vietnam Journal of Mathematics (VJM). Son was the Deputy Editor-in-Chief of VJM in the period 1992–1997 and was one of the initiators of the ever lasting cooperation between this journal and Springer, started from 1999. During the period from 1998 until 2011, Son served as VJM Editor-in-Chief and, on this position, he has made great efforts and contributions to improve the scientific quality and the international reputation of the journal.

On behalf of all the contributors of this special issue and the Editorial Board of Vietnam Journal of Mathematics, we wish Nguyen Khoa Son many further years of good health and happiness.