@Article{alpern85:_defin_liven,
  author = 	 {Bowen Alpern and Fred B.\ Schneider},
  title = 	 {{D}efining {L}iveness},
  journal = 	 {Information Processing Letters},
  year = 	 1985,
  volume =	 21,
  number =	 4,
  pages =	 {181--185},
  month =	 {Oct.}
}


