Yes, Elizabeth Taylor, Norman Mailer, Warren Beatty, David Rockefeller, and Mick Jagger will go to a nightclub, but only if they are reasonably certain that Diana Ross, William F. Buckley Jr., Salvador Dali, Betty Ford, Frank Sinatra, Mikhail Baryshnikov, and the king of Cyprus will show up too--and vice versa.
A group of celebrities will be at the nightclub as long as another specific group is there.