Checking Graph-Transformation Systems for Confluence

In general, it is undecidable whether a terminating graph-transformation system is confluent or not. We introduce the class of coverable hypergraph-transfor- mation systems and show that confluence is decidable for cove rable systems that are terminating. Intuitively, a system is coverable if its typi ng allows to extend each crit- ical pair with a non-deletable context that uniquely identi fies the persistent nodes of the pair. The class of coverable systems includes all hypergraph-transformation sys- tems in which hyperedges can connect arbitrary sequences of nodes, and all graph- transformation systems with a sufficient number of unused ed ge labels.

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