Research is not a solitary activity. I have had the chance of working with many researchers. Let me write down their names below in recognition of my gratitude: thanks for many things that you have taught me and the happy time that we spent together.

Fidaa Abed, Pierre Aboulker, Antonios Antoniadis, Chrisil Arackaparambil, Guillaume Aubian, Umang Bhaskar, Sayan Bhattacharya, Vibhor Bhatt, Parinya Chalermsook, Amit Chakrabarti, Florin Constantin, José Correa, Ágnes Cseh, Lisa Fleischer, Danny Hermelin, Martin Hoefer, Darrell Hoy, Kazuo Iwama, Naonori Kakimura, Naoyuki Kamiyama, Ming-Yang Kao, Telikepalli Kavitha, Stephan Kratsch, Xiang-Yang Li, Mathieu Mari, Simon Mauras, Kurt Mehlhorn, Joe Mitchell, Shuichi Miyazaki, Nabil Mustafa, Danupon Nanongkai, Meghana Nasre, Dimitris Michail, Sebastian Ott, David Parkes, Malvika Rao, Thatchaphol Saranurak, François Sellier, Kevin Schewior, Pattara Sukprasert, Zoya Svitkina, Thatchaphol Saranurak, Theophile Thiery, Yih-Kuen Tsay, José Verschae, Jens Vygen, Lisa Wagner, Magnus Wahlström, Justin Ward, Hiroki Yanagisawa, Sorrachai Yingchareonthawornchai, Yuichi Yoshida.