7 This work was supported by National 973 Program of China (Grant No.2005CB321901) and the fund of the State Key Laboratory of Software Development Envi- ronment (SKLSDE-2008ZX-03). The second author was supported partially by National Natural Science Founda- tion of China (Grant No. 70901002 and 90924020) and Beihang Innovation Platform Funding (Grant. No YMF- 10-04-024). FIG. 7: (Color online) The increment of C when β grows in the log-scale. We perform the experiments for each pair of α and β 20 times and return the mean value as the final result. FIG. 6: (Color online) The variations of C during the removal of ties. The diffusing time is T$_{Facebook}$ = | V | and T$_{Y ouTube}$ = 10 $^{4}$. We perform the experiments 20 times for α = 0 and β = 0 . 01, and return the mean value as the final result. 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 f$_{r}$ C Remove Weak Ties First Remove Strong Ties First (a) Facebook 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 f$_{r}$ C Remove Weak Ties First Remove Strong Ties First (b) YouTube 10 −4 10 −3 10 −2 10 −1 10 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 β C ID(−1, ) ID(0, ) ID(1, ) (a) Facebook 10 −4 10 −3 10 −2 10 −1 10 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 β C ID(−1, ) ID(0, ) ID(1, ) (b) YouTube Acknowledgments 675 (2008). [12] M. Cha, A. Mislove, B. Adams, and K. P. Gummadi, in WOSP’08 (ACM, New York, NY, USA, 2008), pp. 13–18. [13] S. Golder, D. Wilkinson, and B. Huberman, in Proc. 3rd Intl. Conf. on Communities and Technologies (2007). [14] B. Viswanath, A. Mislove, M. Cha, and K. P. Gummadi, in WOSN’09 (ACM, New York, NY, USA, 2009), pp. 37–42. [15] L. Guo, E. Tan, S. Chen, X. Zhang, and Y. E. Zhao, in 15th KDD (2009), pp. 369–378. [16] M. S. Granovetter, American Journal of Sociology 78 , 1360 (1973). [17] M. S. Granovetter, The Strength of Weak Ties (Univer- sity of Chicago Press, 1974). [1] Facebook , http://www.facebook.com . [2] Flickr , http://www.flickr.com . [3] Youtube , http://www.youtube.com . [4] Twitter , http://www.twitter.com . [5] Livejournal , http://www.livejournal.com . [6] Orkut , http://www.orkut.com . [7] Xiaonei , http://www.xiaonei.com . [8] A. Mislove, M. Marcon, K. P. Gummadi, P. Druschel, and B. Bhattacharjee, in 7th IMC (2007), pp. 29–42. [9] Y.-Y. Ahn, S. Han, H. Kwak, S. Moon, and H. Jeong, in 16th WWW (2007), pp. 835–844. [10] F. Fu, X. Chen, L. Liu, and L. Wang, Physics Letters A 371 , 58 (2007). [11] F. Fu, X. Chen, L. Liu, and L. Wang, Physica A 387 ,