Deciding whether a production rule is relational computable

Abstract

In this paper, we consider the problem of integrating a production rule language, named RDL1, with a relational DBMS. A production rule in RDL1, consists of a condition part which is a relational calculus expression and of an action part which is a sequence of database updates. The main problem addressed in this paper is to determine whether a rule program can be computed as a relational algebra program, i.e., whether the initial semantics of the program is not modified by a set-oriented or relational computation. First, we define the syntax and the semantics of the RDL1 language which is given as the sequence of database states reachable by the computation of the program. We conjecture that deciding if a rule is relational computable is an undecidable problem and then, propose sufficient conditions to decide if a rule is relational computable. We present a general method to check the validity of these conditions. Finally, we propose two algorithms which are derived from the previous method. The first one gave sufficient syntactic conditions for a rule to be relational computable. The second one gave sufficient semantic conditions and leads to check integrity constraints over the database to decide whether a rule is relational computable.

Research is supported in part by the Esprit Project ISIDE (under contract P1133).