Error and attack tolerance of BBS virtual community as a scale-free network

BBS virtual community is often subjected to errors and attacks. In order to design new bulletin board systems and protect existing systems, errors and attacks tolerance of BBS virtual community is studied in this paper. Firstly, we constructed the directed BBS reply networks in which identifications are considered as nodes and reply articles set up links. Statistics on BBS reply network show that the degree distribution and betweenness centrality distribution are scale-free. Then, we investigated the ability of BBS reply network to resist errors and attacks simulated by removing randomly selected nodes or targeting some specific classes of important nodes, and found BBS virtual community is highly vulnerable to deliberate attacks on its highest-degree or highest-betweenness nodes.