David Heckerman Ross D. Shachter A Definition and Graphical Representation for Causality. 262-273 1995 conf/uai/1995 UAI http://uai.sis.pitt.edu/displayArticleDetails.jsp?mmnu=1&smnu=2&article_id=442&proceeding_id=11 db/conf/uai/uai1995.html#HeckermanS95