A Set-oriented Meta-interpreter Driven by a \re- Lational" Trace for Deductive Databases Debug- Ging 1

The development of deductive databases requires tools, in particular for de-bugging. Deductive databases manage large quantity of data and, in general, in a set-oriented way. The existing systems of explanation for deductive databases do not take these constraints into account. We propose a tracing technique which consists of integrating a "relational" trace and an instrumented meta-interpreter using substitution sets. The relational trace eeciently gives precise information about data extraction from the relational database. The meta-interpreter manages substitution sets and gives explanation on the deduction. The expensive aspects of meta-interpretation are reduced by the use of the trace which avoids many calculations. The exibility of meta-interpretation is preserved. It allows traces of diierent prooles to be easily produced.