Can the USENET newsgroup system or the SETI@home project be considered distributed systems? (SETI@home uses several million

Question:

Can the USENET newsgroup system or the SETI@home project be considered distributed systems? (SETI@home uses several million idle personal computers to analyze radio telescope data to search for extraterrestrial intelligence.) If so, how do they relate to the categories described in Fig. 8-1?