The Correspondence Between the Logical Algorithms Language and CHR

This paper investigates the relationship between the Logical Algorithms formalism (LA) of Ganzinger and McAllester and Constraint Handling Rules (CHR). We present a translation scheme from LA to CHR: CHR with rule priorities and show that the metacomplexity theorem for LA can be applied to a subset of CHR via inverse translation. This result is compared with previous work. Inspired by the high-level implementation proposal of Ganzinger and McAllester, we demonstrate how LA programs can be compiled into CHR rules that interact with a scheduler written in CHR. This forms the first actual implementation of LA. Our implementation achieves the required complexity for the meta-complexity theorem to hold and can execute a subset of CHR with strong complexity bounds.