I would like to express my deep gratitude to Professor Nguyen Dong Yen and
Dr. Bui Trong Kien for introducing me to Variational Analysis and Optimization Theory. I am thankful to them for their careful and effective supervision.
I am grateful to Professor Ha Huy Bang for his advice and kind help. My
many thanks are addressed to Professor Hoang Xuan Phu, Professor Ta Duy
Phuong, and Dr. Nguyen Huu Tho, for their valuable support.
During my long stays in Hanoi, I have had the pleasure of contacting
with the nice people in the research group of Professor Nguyen Dong Yen. In
particular, I have got several significant comments and suggestions concerning
the results of Chapters 2 and 3 from Professor Nguyen Quang Huy. I would
like to express my sincere thanks to all the members of the research group.
I owe my thanks to Professor Daniel Frohardt who invited me to work at
Department of Mathematics, Wayne State University, for one month (September 1–30, 2011). I would like to thank Professor Boris Mordukhovich who
gave me many interesting ideas in the five seminar meetings at the Wayne
State University in 2011 and in the Summer School “Variational Analysis
and Applications” at Institute of Mathematics (VAST, Hanoi) and Vietnam
Institute Advanced Study in Mathematics in 2012.
This dissertation was typeset with LaTeX program. I am grateful to Professor Donald Knuth who created TeX the program. I am so much thankful
to MSc. Le Phuong Quan for his instructions on using LaTeX.
I would like to thank the Board of Directors of Institute of Mathematics
(VAST, Hanoi) for providing me pleasant working conditions at the Institute.
I would like to thank the Steering Committee of Cantho University a lot
for constant support and kind help during many years.
Financial supports from the Vietnam National Foundation for Science
and Technology Development (NAFOSTED), Cantho University, Institute of
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Mathematics (VAST, Hanoi), and the Project “Joint research and training
on Variational Analysis and Optimization Theory, with oriented applications
in some technological areas” (Vietnam-USA) are gratefully acknowledged.
I am so much indebted to my parents, my sisters and brothers, for their
love and support. I thank my wife for her love and encouragement
