简介：NondeterminismofPROLOGexecutionrequiresthatablockofcontrolinformationorachoicepointforeachprocedurecallbestoredwhenthereareothercandidateclausestobeused.Whenthecurrentlyselectedclausefails,thebindingsmadebytheclausemustbeundoneandthestoredchoicepointisreactivated,andthenanotherclauseofthecandidateonesischosentorunonit.StoringandreactivatingchoicepointsandundoingaccountforthegreatoverheadarerequiredtocontrolPROLOGexecution,whichisquitedifferentfromconventionalprograms.ThispaperfocusesonthetechniquesusedinSequentialPROLOGEngine(SPE)toreducetheoverheadofcontroloperations.ThecontrolinstructionsofSPEstorenomorechoicepointsthanthenecessary.Itsarchitecturetakestheapproachesofanalysingthepotentialparallelisminthecontroloperationsanddevelopingafractionofitduetothecost-effectconsideration.TheresultsofexecutingtwosampleprogramsonSPEintheformofhandtimingsarepresented,whichfavortheapproach.