Myrtle: A Set-Oriented Meta-Interpreter Driven by a "Relational" Trace for Deductive Databases Debugging

Deductive databases manage large quantities 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 e ciently 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 di erent pro les of trace to be easily produced. Key-words: deductive databases, debugging, trace, multi-SLD-AL, meta-interpreter, substitution set, instrumentation