A community server categorizes and accumulates messages exchanged by users on a virtual community for respective topics. The community server includes a user access limiting control unit. The user access limiting control unit determines user's access authority of each client terminal for each community...http://www.google.de/patents/US20030028596?utm_source=gb-gplus-sharePatent US20030028596 - Community-based collaborative knowledge system, and user access limiting method in that system
