[1] GAREY M R, JOHNSON D S. Computers and intractability: a guide to the theory of NP-completeness: series of books in the mathematical sciences [M]. San Francisco: Freeman, 1979: 190-205. [2] LEWIS J M. The node-deletion problem for hereditary properties is NP-complete [J]. Journal of Computer and System Sciences, 1980, 20(2): 219-230. [3] CAI L. Fixed-parameter tractability of graph modification problems for hereditary properties [J]. Information Processing Letters, 1996, 58(4): 171-176. [4] RON SHAMIR A, RODED SHARAN B, DEKEL TSUR A. Cluster graph modification problems [J]. Discrete Applied Mathematics, 2004, 144(1/2): 173-182. [5] GUO J. A more effective linear kernelization for cluster editing [J]. Theoretical Computer Science, 2009, 410(8/9/10): 718-726. [6] CHEN J, MENG J. A 2k kernel for the cluster editing problem [J]. Journal of Computer and System Sciences, 2012, 78(1): 211-220. [7] HUFFNER F, KOMUSIEWICZ C, MOSER H, [WTBX]et al.[WTBZ] Fixed-parameter algorithms for cluster vertex deletion [J]. Theory of Computing Systems, 2008, 47(1): 196-217. [8] BORA A, CYGAN M, KOCIUMAKA T, [WTBX]et al.[WTBZ] Fast branching algorithm for cluster vertex deletion [C]//CSR 2014: Proceedings of the 9th International Computer Science Symposium in Russia. Berlin: Springer, 2014: 111-124. [9] NIEDERMEIER R, ROSSMANITH P. An efficient fixed-parameter algorithm for 3-hitting set [J]. Journal of Discrete Algorithms, 2003, 1(1): 89-102. [10] CAI X. Linear kernelizations for restricted 3-hitting set problems [J]. Information Processing Letters, 2009, 109(13): 730-738. [11] ABU-KHZAM F N. A kernelization algorithm for d-hitting set [J]. Journal of Computer and System Sciences, 2010, 76(7): 524-531.