Towards a Generic Framework to Generate Explanatory Traces of Constraint Solving and Rule-Based Reasoning

In this report, we show how to use the Simple Fluent Calculus (SFC) to specify generic tracers, i.e. tracers which produce a generic trace. A generic trace is a trace which can be produced by different implementations of a software component and used independently from the traced component. This approach is used to define a method for extending a java based CHRor platform called CHROME (Constraint Handling Rule Online Model-driven Engine) with an extensible generic tracer. The method includes a tracer specification in SFC, a methodology to extend it, and the way to integrate it with CHROME, resulting in the platform CHROME-REF (for Reasoning Explanation Facilities), which is a constraint solving and rule based reasoning engine with explanatory traces

Efficient Lazy Evaluation of Rule-Based Programs

Abstract—Thirty years after Forgy’s seminal dissertation, Rete remains the de facto standard matching algorithm. Despite promising research results, alternative algorithms such as TREAT and LEAPS have had little impact on modern production rule engines. Constraint Handling Rules (CHR) is a high-level, declarative programming language, similar to production rules. In recent years, CHR has increasingly been used in a wide range of general-purpose applications. State-of-the-art CHR systems use LEAPS-like lazy matching, and implement a large body of novel program analyses and optimization techniques to further improve performance. While obviously related, CHR and production rules research have mostly evolved independently from each other. With this article, we aim to foster cross-fertilization of implementation techniques. We provide a lucid, comprehensive overview of CHR’s rule evaluation methodology, and survey recent contributions to the field of lazy matching. Our empirical evaluation confirms Rete-based engines would surely benefit from incorporating similar techniques and optimizations