Deciding Eventual Consistency for a Simple Class of Relational Transducer Networks

Abstract

Networks of relational transducers can serve as a formal model for declarative networking, focusing on distributed database querying applications. In declarative networking, a crucial property is eventual consistency, meaning that the final output does not depend on the message delays and re-orderings caused by the network. Here, we show that eventual consistency is decidable when the transducers satisfy some syntactic restrictions, some of which have also been considered in earlier work on automated verification of relational transducers. This simple class of transducer networks computes exactly all distributed queries expressible by unions of conjunctive queries with negation.