明天就答辩了，几年过来，非常感谢大家的指导和帮助。

尽管天资愚钝，无所建树，但是还是从和大家的合作中学到了很多东西。相比5年前，至少是成熟了一些吧。

附上博士论文致谢！！

Huge thanks to my supervisor Yi-Cheng Zhang who has introduced to me the promising and amusing direction of information physics, which eventually become the main focus of my PhD study. In particular, he has built up a room for independent exploration with creative freedom. All I have learned from him will become priceless treasure throughout my whole career.

Before I went to Fribourg, I was a graduate student under Prof. Bing-HongWang. He is the one who firstly displayed the beautiful macroscopic picture of statistical physics, especially how it works in many real systems. After him, I made the decision to throw myself into the statistical physics study. He turned my life around at the“bifurcation point”when I was thinking about to be a computer engineer.

I feel indebted to all my collaborators who helped me much and make the things easy, otherwise I could not imagine to finish this thesis in time. To be specific, results presented in Chapter 2 were obtained in collaboration with Mingsheng Shang and Linyuan Lu, results presented in Chapter 3 with Linyuan Lu and Ci-Hang Jin, results presented in Chapter 4 with Matus Medo, Jie Ren, Tao Li, Fan Yang, Luo-Luo Jiang, Ri-Qi Su, Duo Sun, Jian-Guo Liu, Run-Ran Liu, Chun-Xiao Jia, Zoltan Kuscsik, Joesph Wakeling, Linyuan Lu, Wei Zeng and Zi-Ke Zhang, and results presented in Chapter 5 with Matus Medo.

The full list of my collaborators in various interesting scientific directions is probably too long to write down but would have to include the following: Wen-Jie Bai, Shou-Liang Bu, Hong-An Che, En-Hong Chen, Guan-Rong Chen, Michael Zhi-Qiang Chen, Shi-Min Cai, Kan Chen, Yu-Han Chen, Su-Qi Cheng, Zeng-Ru Di, Ying Fan, Chuan-Ji Fu, Zhong-Qian Fu, Zhi-Ming Gu, Jin-Li Guo, Qiang Guo, Xiao-Pu Han, Da-Ren He, Petter Holme, Bambi Hu, Bo Hu, Chin-Kun Hu, Da-Yan Hua, Pak-Ming Hui, Chun-Xiao Jia, Luo-Luo Jiang, Pin-Qun Jiang, Ci-Hang Jin, Ying-Di Jin, Hoang Anh-Tuan Kiet, Beom Jun Kim, Zoltan Kuscsik, Ying-Cheng Lai, Han-Xiong Li, Ji Li, Meng-Hui Li, Nan-Nan Li, Ping Li, Tao Li, Wei Li, Hong-Kun Liu, Jian-Guo Liu, Jun Liu, Run-Ran Liu, Yu-Feng Lu, Linyuan Lu, Xiao-Shu Luo, Jan Maciejowski, Matus Medo, Qing Ou, Li-Qian Peng, Matjaz Perc, Jie Ren, Ming-Sheng Shang, Da-Ning Shi, Guy-Bart Stan, Ri-Qi Su, Duo Sun, Bao-Mei Tian, Liang Tian, Joesph Wakeling, Bing Wang, Bing-Hong Wang, Da-Hui Wang, Li-Na Wang, Wen-Xu Wang, Yong-Li Wang, Zhong-Tuo Wang, Jin-Shan Wu, Xiang Wu, Zhi-Xi Wu, Biao Xiang, Wei-Ke Xiao, Yan-Bo Xie, Jun-Ming Xu, Xin-Jian Xu, Gang Yan, Chun-Xia Yang, Fan Yang, Han-Xin Yang, Hui-Jie Yang, Qing-Feng Yang, Rui Yang, Chuan-Yang Yin, Guo-Qiang Zhang, Guo-Qing Zhang, Hai-Tao Zhang, Jie Zhang, Ning Zhang, Yi-Cheng Zhang, Zi-Ke Zhang, Ming Zhao, Yang Zhao, Changsong Zhou, Pei-Ling Zhou, Chen-Ping Zhu, Jun-Fang Zhu.

Above all, I thank to my parents for their encouragement and support.