@techreport{West2002-actor,
  author	= {West, Matthew},
  title		= {A spatio-temporal model of activity and state},
  institution	= {Shell Information Technology International Ltd, UK},
  year		= {2002},
  note		= {Written as preparation for the National Science Foundation ACTOR 2002 conference},
  URL		= {http://www.matthew-west.org.uk/Documents/Spatio-temporal-Paradigm.pdf},
  pdf		= {http://www.matthew-west.org.uk/Documents/Spatio-temporal-Paradigm.pdf}
}