Problem. I have been wondering how i can use the set theory to determine the which items form a subset of another in oracle. I wanted to deduct a regimen of drugs from a prescription and what i had to do was to loop through all regimens and find out which one exists in the current prescription. A regimen is a combination of drugs and how they are administered. e.g. to treat Tubercolosis the doctor may prescribe a regimen called (RHE 150/75/275) which is composed of Rifampicin 150 mg/Isoniazid 75 ......