The Impact of Disjunction on Reasoning under Existential Rules: Research Summary

ABSTRACT. Datalogis a Datalog-based language family enhanced with existential quantification in rule heads, equalities and negative constraints. Query answering over databases with respect to a Datalog theory is generally undecidable, however several syntactic restrictions have been proposed to remedy this fact. However there are still open problems regarding these decidable fragments. A very useful and natural feature however is missing from Datalog: The ability to express uncertain knowledge, or choices, using disjunction. In my doctoral studies we endeavour to investigate the impact of adding these feature to known Datalog languages.