  <a href="http://www.cs.cornell.edu/Info/People/sam/sam.html">Sam</a>, <a href="http://www.cdf.toronto.edu:/DCS/CSRI/Hadzilacos.html">Vassos</a>, and I showed that it is impossible to solve the group membership problem in purely asynchronous systems (click <a href="http://www.cs.cornell.edu/Info/People/chandra/GMS-Impossibility.html">here</a> to find out more).<p>
