conf/vldb/87 Stefano Ceri Letizia Tanca Optimization of Systems of Algebraic Equations for Evaluating Datalog Queries. 31-41 1987 VLDB db/conf/vldb/vldb87.html#CeriT87 db/conf/vldb/CeriT87.html VLDB87/P031.PDF conf/popl/AhoU79 conf/pods/BancilhonMSU86 conf/sigmod/BancilhonR86 ... conf/pods/CosmadakisK86 conf/icalp/CourcelleKV74 conf/vldb/CeriGL86 ... conf/sigmod/Finkelstein82 conf/sigmod/GardarinM86 journals/jacm/HenschenN84 conf/icdt/KiferL86 journals/tods/Ullman85