A new recursive subclass of domain independent formulas based on subimplication

We motivate and define subimplication completion of a relational calculus query and of a general deductive database. Subimplication completion not only avoids getting unexpected answers, but also makes some domain dependent queries and databases domain independent. We define a new recursive subclass of domain independent formulas, called weakly range-restricted formulas, which is strictly larger than the class of range-restricted formulas. We also define admissible and deductive databases and show that under the subimplication completion they are domain independent and safe.<>