TY - JOUR AU - Wang, Zhe AU - Wang, Kewen AU - Zhang, Xiaowang PY - 2018/04/25 Y2 - 2024/03/28 TI - Forgetting and Unfolding for Existential Rules JF - Proceedings of the AAAI Conference on Artificial Intelligence JA - AAAI VL - 32 IS - 1 SE - AAAI Technical Track: Knowledge Representation and Reasoning DO - 10.1609/aaai.v32i1.11552 UR - https://ojs.aaai.org/index.php/AAAI/article/view/11552 SP - AB - <p> Existential rules, a family of expressive ontology languages, inherit desired expressive and reasoning properties from both description logics and logic programming. On the other hand, forgetting is a well studied operation for ontology reuse, obfuscation and analysis. Yet it is challenging to establish a theory of forgetting for existential rules. In this paper, we lay the foundation for a theory of forgetting for existential rules by developing a novel notion of unfolding. In particular, we introduce a definition of forgetting for existential rules in terms of query answering and provide a characterisation of forgetting by the unfolding. A result of forgetting may not be expressible in existential rules, and we then capture the expressibility of forgetting by a variant of boundedness. While the expressibility is undecidable in general, we identify a decidable fragment. Finally, we provide an algorithm for forgetting in this fragment. </p> ER -