The new DLV Grounder: External Computations, Interoperability and Customizability

I-DLV is the new intelligent grounder of DLV; while relying on the solid theoretical foundations of its predecessor, it has been redesigned and re-engineered ex-novo, both in algorithms and data structures. It now features full support to ASP-Core-2 standard language, deductive database capabilities, increased flexibility, significantly improved performance, and an extensible design that eases the incorporation of optimization techniques, language updates and customizability. In this paper we present I-DLV, focusing on most recent advancements that mainly aim at easing the integration with external systems: the handling of external computations with explicit calls to Python scripts via external atoms, and interoperability mechanisms for the connection with relational and graph databases via explicit directives for importing/exporting data; furthermore, we discuss how the fine-grained customizability means allow to control the the internal grounding process, possibly positively aecting performance.