When designing a deductive database, the designer has to decide for ea
ch predicate (or relation) whether it should be defined extensionally
ol intensionally and what the definition should look like. An intellig
ent interactive system is presented to assist the designer in this tas
k. It starts from an example state of a database in which all predicat
es ale defined extensionally. It can then compact the database by tran
sforming extensionally defined predicates into intensionally defined o
nes. These predicates can be chosen by the user or by the system itsel
f: Further compaction is possible by inventing new predicates; this in
vention is controlled by user-specified templates. The system also pro
poses semantic integrity constraints to the user. These do not lead to
extra compaction but can be used to make the database more robust. Th
e intelligent system employs techniques from the area of inductive log
ic programming.