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G. Gottlob, M. Manna, A. Pieris:
"Polynomial Combined Rewritings for Linear Existential Rules and DL-Lite with n-ary Relations";
Talk: 28th International Workshop on Description Logics, Athens,Greece; 06-07-2015 - 06-10-2015; in: "Proceedings of the 28th International Workshop on Description Logics, Athens,Greece, June 7-10, 2015", CEUR Workshop Proceedings, 1350 (2015), 4 pages.

This paper considers the setting of ontology-based query answering (OBQA). In this
setting, Description Logics (DLs) and existential rules (a.k.a. tuple-generating dependencies
or Datalog± rules) are popular ontology languages, while conjunctive queries
(CQs) is the main querying tool. Among KR researchers there is a clear consensus that
the required level of scalability in OBQA can only be achieved via query rewriting,
which attempts to reduce OBQA into the problem of evaluating a query over a relational
database. Two query languages are usually considered: first-order queries (FO)
and non-recursive Datalog queries (NDL).
An interesting approach to query rewriting is the polynomial combined approach [7],
which can be described as follows: an ontology Σ can be incorporated together with a
CQ q into a database query qΣ in polynomial time, and also with a database D into
a database DΣ in polynomial time, such that qΣ over DΣ yields the same result as q
evaluated over the knowledge base consisting of D and Σ. The polynomial combined
approach has been applied to ELHdr
⊥ [7], an extension of the well-known DL EL, to
DL-LiteN
horn [5, 6], one of the most expressive logics of the DL-Lite family, and only
recently to the main guarded- and sticky-based classes of existential rules [3].

http://ceur-ws.org/Vol-1350/paper-22.pdf

Project Head Stefan Woltran:
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