Georg Lausen Bertram Ludäscher Wolfgang May On Active Deductive Databases: The Statelog Approach. 69-106 1998 conf/dagstuhl/1998change Transactions and Change in Logic Databases http://link.springer.de/link/service/series/0558/bibs/1472/14720069.htm db/conf/dagstuhl/change9697.html#LausenLM98a