Timothy Griffin Leonid Libkin Howard Trickey An Improved Algorithm for the Incremental Recomputation of Active Relational Expressions. 508-511 1997 9 IEEE Trans. Knowl. Data Eng. 3 db/journals/tkde/tkde9.html#GriffinLT97 db/journals/tkde/GriffinLT97.html journals/tkde/QianW91 conf/sigmod/GriffinL95