{"type":"ScholarlyArticle","title":"Query Answering for Existential Rules via Efficient Datalog Rewriting","authors":[{"name":"Zhe Wang","slug":"zhe-wang","given":"Zhe","family":"Wang","affiliation":"Griffith University , Australia"},{"name":"Peng Xiao","slug":"peng-xiao","given":"Peng","family":"Xiao","affiliation":"Griffith University , Australia"},{"name":"Kewen Wang","slug":"kewen-wang","given":"Kewen","family":"Wang","affiliation":"Griffith University , Australia"},{"name":"Zhiqiang Zhuang","slug":"zhiqiang-zhuang","given":"Zhiqiang","family":"Zhuang","affiliation":"Tianjin University , China"},{"name":"Hai Wan","slug":"hai-wan","given":"Hai","family":"Wan","affiliation":"Sun Yat-sen University , China"}],"abstract":"Existential rules are an expressive ontology formalism for ontology-mediated query answering and thus query answering is of high complexity, while several tractable fragments have been identified. Existing systems based on first-order rewriting methods can lead to queries too large for DBMS to handle. It is shown that datalog rewriting can result in more compact queries, yet previously proposed datalog rewriting methods are mostly inefficient for implementation. In this paper, we fill the gap by proposing an efficient datalog rewriting approach for answering conjunctive queries over existential rules, and identify and combine existing fragments of existential rules for which our rewriting method terminates. We implemented a prototype system Drewer, and experiments show that it is able to handle a wide range of benchmarks in the literature. Moreover, Drewer shows superior or comparable performance over state-of-the-art systems on both the compactness of rewriting and the efficiency of query answering.","doi":"10.24963/ijcai.2020/268","url":"https://ijcai.org/proceedings/2020/268","pdf":"https://ijcai.org/proceedings/2020/0268.pdf","markdown":"https://ijcai.org/proceedings/2020/268.md","bibtex":"https://ijcai.org/proceedings/2020/bibtex/268","volume":{"slug":"2020","title":"Proceedings of the Twenty-Ninth International Joint Conference on Artificial Intelligence","short_title":"IJCAI 2020","url":"https://ijcai.org/proceedings/2020/","year":2020,"location":"Yokohama","dates":"January 2021 (postponed from 11-17 July 2020)","editors":"Christian Bessiere","isbn":"978-0-9992411-6-5","publisher":"International Joint Conferences on Artificial Intelligence Organization","doi_prefix":"10.24963/ijcai.2020"},"section":"Knowledge Representation and Reasoning","track":"Main track","number":268,"pages":{"first":1933,"last":1939},"keywords":["Knowledge Representation and Reasoning: Description Logics and Ontologies"],"videos":[{"label":"Video","url":"https://videos.ijcai20.org/25050/file_25050.m3u8","length_sec":275,"provider":"hls"}],"references":[{"position":1,"raw":"[Ahmetaj et al., 2018] S. Ahmetaj, M. Ortiz, and M. Simkus. Rewriting guarded existential rules into small datalog pro- grams. In Proc. of ICDT, pages 4:1-4:24, 2018.","title":"Rewriting guarded existential rules into small datalog programs","authors":"S Ahmetaj, M Ortiz, M Simkus","year":"2018","venue":"Proc. of ICDT","doi":null,"url":null,"internal_url":null},{"position":2,"raw":"[Baget et al., 2011] J.-F. Baget, M. Leclère, M.-L. Mugnier, and E. Salvat. On rules with existential variables: Walking the decidability line. Artif. Intell., 175(9-10):1620-1654, 2011.","title":"On rules with existential variables: Walking the decidability line","authors":"J.-F Baget, M Leclère, M.-L Mugnier, E Salvat","year":"2011","venue":"Artif. Intell","doi":null,"url":null,"internal_url":null},{"position":3,"raw":"[Benedikt et al., 2017] M. Benedikt, G. Konstantinidis, G. Mecca, B. Motik, P. Papotti, D. Santoro, and E. Tsamoura. Benchmarking the chase. In Proc. of PODS, pages 37-52, 2017.","title":"Benchmarking the chase","authors":"M Benedikt, G Konstantinidis, G Mecca, B Motik, P Papotti, D Santoro, E Tsamoura","year":"2017","venue":"Proc. of PODS","doi":null,"url":null,"internal_url":null},{"position":4,"raw":"[Benedikt et al., 2018] M. Benedikt, B. Motik, and E. Tsamoura. Goal-driven query answering for exis- tential rules with equality. In Proc. of AAAI, pages 1761-1770, 2018.","title":"Goal-driven query answering for existential rules with equality","authors":"M Benedikt, B Motik, E Tsamoura","year":"2018","venue":"Proc. of AAAI","doi":null,"url":null,"internal_url":null},{"position":5,"raw":"[Bienvenu et al., 2014] M. Bienvenu, B. ten Cate, C. Lutz, and F. Wolter. Ontology-based data access: A study through disjunctive datalog, csp, and MMSNP. ACM Trans. Database Syst., 39(4):33:1-33:44, 2014.","title":"Ontology-based data access: A study through disjunctive datalog, csp, and MMSNP","authors":"M Bienvenu, B Cate, C Lutz, F Wolter","year":"2014","venue":"ACM Trans. Database Syst","doi":null,"url":null,"internal_url":null},{"position":6,"raw":"[Bienvenu et al., 2017] M. Bienvenu, S. Kikot, R. Kontchakov, V. V. Podolskii, V. Ryzhikov, and M. Zakharyaschev. The complexity of ontology-based data access with OWL 2 QL and bounded treewidth queries. In Proc. of PODS, pages 201-216, 2017.","title":"The complexity of ontology-based data access with OWL 2 QL and bounded treewidth queries","authors":"M Bienvenu, S Kikot, R Kontchakov, V V Podolskii, V Ryzhikov, M Zakharyaschev","year":"2017","venue":"Proc. of PODS","doi":null,"url":null,"internal_url":null},{"position":7,"raw":"[Calì et al., 2012a] A. Calì, G. Gottlob, and T. Lukasiewicz. A general datalog-based framework for tractable query an- swering over ontologies. J. Web Sem., 14:57-83, 2012.","title":"A general datalog-based framework for tractable query answering over ontologies","authors":"Calì","year":"2012","venue":"J. Web Sem","doi":null,"url":null,"internal_url":null},{"position":8,"raw":"[Calì et al., 2012b] A. Calì, G. Gottlob, and A. Pieris. To- wards more expressive ontology languages: The query an- swering problem. Artif. Intell., 193:87-128, 2012.","title":"Towards more expressive ontology languages: The query answering problem","authors":"Calì","year":"2012","venue":"Artif. Intell","doi":null,"url":null,"internal_url":null},{"position":9,"raw":"[Calì et al., 2013] A. Calì, G. Gottlob, and M. Kifer. Taming the infinite chase: Query answering under expressive rela- tional constraints. J. Artif. Intell. Res., 48:115-174, 2013.","title":"Taming the infinite chase: Query answering under expressive relational constraints","authors":"A Calì, G Gottlob, M Kifer","year":"2013","venue":"J. Artif. Intell. Res","doi":null,"url":null,"internal_url":null},{"position":10,"raw":"[Carral et al., 2019] D. Carral, I. Dragoste, L. González, C. J. H. Jacobs, M. Krötzsch, and J. Urbani. Vlog: A rule engine for knowledge graphs. In Proc. of ISWC, pages 19-35, 2019.","title":"Vlog: A rule engine for knowledge graphs","authors":"D Carral, I Dragoste, L González, C J H Jacobs, M Krötzsch, J Urbani","year":"2019","venue":"Proc. of ISWC","doi":null,"url":null,"internal_url":null},{"position":11,"raw":"[Eiter et al., 2012] T. Eiter, M. Ortiz, M. Simkus, T.-K. Tran, and G. Xiao. Query rewriting for Horn-SHIQ plus rules. In Proc. of AAAI, 2012.","title":"Query rewriting for Horn-SHIQ plus rules","authors":"T Eiter, M Ortiz, M Simkus, T.-K Tran, G Xiao","year":"2012","venue":"Proc. of AAAI","doi":null,"url":null,"internal_url":null},{"position":12,"raw":"[Gottlob and Schwentick, 2012] G. Gottlob and T. Schwentick. Rewriting ontological queries into small nonrecursive datalog programs. In Proc. of KR, 2012.","title":"Rewriting ontological queries into small nonrecursive datalog programs","authors":"G Gottlob, T Schwentick","year":"2012","venue":"Proc. of KR","doi":null,"url":null,"internal_url":null},{"position":13,"raw":"[Gottlob et al., 2014a] G. Gottlob, G. Orsi, and A. Pieris. Query rewriting and optimization for ontological databases. ACM Trans. Database Syst., 39(3):25:1-25:46, 2014.","title":"Query rewriting and optimization for ontological databases","authors":"Gottlob","year":"2014","venue":"ACM Trans. Database Syst","doi":null,"url":null,"internal_url":null},{"position":14,"raw":"[Gottlob et al., 2014b] G. Gottlob, S. Rudolph, and M. Simkus. Expressiveness of guarded existential rule languages. In Proc. of PODS, pages 27-38, 2014.","title":"Expressiveness of guarded existential rule languages","authors":"Gottlob","year":"2014","venue":"Proc. of PODS","doi":null,"url":null,"internal_url":null},{"position":15,"raw":"[Grau et al., 2013] B. C. Grau, I. Horrocks, M. Krötzsch, C. Kupke, D. Magka, B. Motik, and Z. Wang. Acyclicity notions for existential rules and their application to query answering in ontologies. J. Artif. Intell. Res., 47:741-808, 2013.","title":"Acyclicity notions for existential rules and their application to query answering in ontologies","authors":"B C Grau, I Horrocks, M Krötzsch, C Kupke, D Magka, B Motik, Z Wang","year":"2013","venue":"J. Artif. Intell. Res","doi":null,"url":null,"internal_url":null},{"position":16,"raw":"[Hansen et al., 2015] P. Hansen, C. Lutz, I. Seylan, and F. Wolter. Efficient query rewriting in the description logic EL and beyond. In Proc. of IJCAI, pages 3034-3040, 2015.","title":"Efficient query rewriting in the description logic EL and beyond","authors":"P Hansen, C Lutz, I Seylan, F Wolter","year":"2015","venue":"Proc. of IJCAI","doi":null,"url":null,"internal_url":"/proceedings/2015/428"},{"position":17,"raw":"[König et al., 2015a] M. König, M. Leclère, and M.-L. Mug- nier. Query rewriting for existential rules with compiled preorder. In Proc. of IJCAI, pages 3106-3112, 2015.","title":"Query rewriting for existential rules with compiled preorder","authors":"König","year":"2015","venue":"Proc. of IJCAI","doi":null,"url":null,"internal_url":"/proceedings/2015/438"},{"position":18,"raw":"[König et al., 2015b] M. König, M. Leclère, M.-L. Mugnier, and M. Thomazo. Sound, complete and minimal UCQ- rewriting for existential rules. Semantic Web, 6(5):451- 475, 2015.","title":"Sound, complete and minimal UCQrewriting for existential rules","authors":"König","year":"2015","venue":"Semantic Web","doi":null,"url":null,"internal_url":null},{"position":19,"raw":"[Kontchakov et al., 2010] R. Kontchakov, C. Lutz, D. Toman, F. Wolter, and M. Zakharyaschev. The combined approach to query answering in DL-Lite. In Proc. of KR, 2010. Leclère et al., 2016]","title":"The combined approach to query answering in DL-Lite","authors":"R Kontchakov, C Lutz, D Toman, F Wolter, M Zakharyaschev","year":"2010","venue":"Proc. of KR","doi":null,"url":null,"internal_url":null},{"position":20,"raw":"M. Leclère, M.-L. Mugnier, and F. Ul- liana. On bounded positive existential rules. In Proc. of DL, 2016.","title":"On bounded positive existential rules","authors":"M Leclère, M.-L Mugnier, F Ulliana","year":"2016","venue":"Proc. of DL","doi":null,"url":null,"internal_url":null},{"position":21,"raw":"[Leone et al., 2019] N. Leone, M. Manna, G. Terracina, and P. Veltri. Fast query answering over existential rules. ACM Trans. Comput. Log., 20(2):12:1-12:48, 2019.","title":"Fast query answering over existential rules","authors":"N Leone, M Manna, G Terracina, P Veltri","year":"2019","venue":"ACM Trans. Comput. Log","doi":null,"url":null,"internal_url":null},{"position":22,"raw":"[Pérez-Urbina et al., 2010] H. Pérez-Urbina, B. Motik, and I. Horrocks. Tractable query answering and rewriting under description logic constraints. J. Applied Logic, 8(2):186-209, 2010.","title":"Tractable query answering and rewriting under description logic constraints","authors":"H Pérez-Urbina, B Motik, I Horrocks","year":"2010","venue":"J. Applied Logic","doi":null,"url":null,"internal_url":null},{"position":23,"raw":"[Rosati and Almatelli, 2010] R. Rosati and A. Almatelli. Im- proving query answering over DL-Lite ontologies. In Proc. of KR, 2010.","title":"Improving query answering over DL-Lite ontologies","authors":"R Rosati, A Almatelli","year":"2010","venue":"Proc. of KR","doi":null,"url":null,"internal_url":null},{"position":24,"raw":"[Stefanoni et al., 2013] G. Stefanoni, B. Motik, and I. Hor- rocks. Introducing nominals to the combined query an- swering approaches for EL. In Proc. of AAAI, 2013.","title":"Introducing nominals to the combined query answering approaches for EL","authors":"G Stefanoni, B Motik, I Horrocks","year":"2013","venue":"Proc. of AAAI","doi":null,"url":null,"internal_url":null},{"position":25,"raw":"[Trivela et al., 2015] D. Trivela, G. Stoilos, A. Chortaras, and G. B. Stamou. Optimising resolution-based rewriting algorithms for OWL ontologies. J. Web Semant., 33:30- 49, 2015.","title":"Optimising resolution-based rewriting algorithms for OWL ontologies","authors":"D Trivela, G Stoilos, A Chortaras, G B Stamou","year":"2015","venue":"J. Web Semant","doi":null,"url":null,"internal_url":null},{"position":26,"raw":"[Venetis et al., 2016] T. Venetis, G. Stoilos, and V. Vassa- los. Rewriting minimisations for efficient ontology-based query answering. In Proc. of ICTAI, pages 1095-1102, 2016.","title":"Rewriting minimisations for efficient ontology-based query answering","authors":"T Venetis, G Stoilos, V Vassalos","year":"2016","venue":"Proc. of ICTAI","doi":null,"url":null,"internal_url":null},{"position":27,"raw":"[Wang et al., 2018] Z. Wang, K. Wang, and X. Zhang. For- getting and unfolding for existential rules. In Proc. of AAAI, pages 2013-2020, 2018.","title":"Forgetting and unfolding for existential rules","authors":"Z Wang, K Wang, X Zhang","year":"2018","venue":"Proc. of AAAI","doi":null,"url":null,"internal_url":null},{"position":28,"raw":"[Zhou et al., 2015] Y. Zhou, B. C. Grau, Y. Nenov, M. Kaminski, and I. Horrocks. Pagoda: Pay-as-you-go ontology query answering using a datalog reasoner. J. Ar- tif. Intell. Res., 54:309-367, 2015.","title":"Pagoda: Pay-as-you-go ontology query answering using a datalog reasoner","authors":"Y Zhou, B C Grau, Y Nenov, M Kaminski, I Horrocks","year":"2015","venue":"J. Artif. Intell. Res","doi":null,"url":null,"internal_url":null}],"license_note":"Copyright International Joint Conferences on Artificial Intelligence."}