Mutation: in this paper, we adopt the following mutation mode: randomly select a gene of a chromosome, and change its value to an integer in the set of {1, 2, ..., L}, where L is the largest class number in that chromosome. It is easy to operate and contributes a lot to increase the diversity of population. Besides, invalid mutation will be effectively avoided through limiting the scope of mutation. For each of the chromosome to be mutated, 20% genes will be selected to operate mutation. For example, if the chromosome rm=[1 2 1 1 3] is selected, then L should equal to 3. Select 20% genes (namely one gene) randomly, assuming it is the fourth vertex, then its corresponding value of gene can be turned into any one among 1, 2 and 3. The whole process is shown in TABLE 5.
TABLE5: Mutation operation v rm …show more content…
SFI consists of 118 vertices, which represent the largest component of the Santa Fe Institute collaboration network. There are about 200 edges in this network.
The netscience network is a coauthorship network of 1589 scientists working on network theory and experiment. As this paper deals with only unweighted networks, we will regard this weighted network as unweighted one.
The Power grid network is an undirected, unweighted network representing the topology of the Western States Power Grid of the United States, in which 4941 power base stations transmit electricity through 6594 transmission lines.
The second largest network tested in this paper is PGP, the giant component of the network of users of the Pretty-Good-Privacy algorithm for secure information interchange. This network consists of 10680 nodes and 24340 edges.
The last network we used here is Internet network which contains 22963 nodes and 48436 edges which is the snapshot of the structure of the Internet network.
4. 2. Evaluation