Lazy Context Cloning for Non-Deterministic Graph Rewriting ⋆

We define a rewrite strategy for a class of non-confluent constructor-based term graph rewriting systems and prove its correctness. Our strategy and its extension to narrowing are intended for the implementation of non-strict non-deterministic functional logic programming languages. Our strategy is based on a graph transformation, called bubbling, that avoids the construction of large contexts of redexes with distinct replacements, an expensive and frequently wasteful operation executed by competitive complete techniques.