Improving Refutational Completeness of Relational Search via Divergence Test
Dmitry Rozplokhas, Dmitry Boulytchev · 2018
We describe a search optimization technique for implementation of relational programming language miniKanren which makes more queries converge. Specifically, we address the problem of conjunction non-commutativity. Our technique is based on a certain divergence criterion that we use to trigger a dynamic reordering of conjuncts. We present a formal semantics of a miniKanren-like language and prove that our optimization does not compromise already converging programs, thus, being a proper improvement. We also present the prototype implementation of the improved search and demonstrate its application for a number of realistic specifications.