Section: New Results

Semantic Query Answering

Building upon last year's work on regular path queries, we studied the complexity of answering conjunctive regular path queries under linear existential rules and under guarded existential rules. These queries generalized conjunctive queries by their ability to check for a path between two individuals which is labeled by a word belonging to a given regular language. Linear and guarded rules are widely recognized as two important classes of existential rules, that among other generalizes most popular Horn description logics. The results are quite positive, in the sense that the complexity is as good as we could hope for: we provided matching upper-bound that correspond to much less expressive query or ontology languages (i.e., they come from RPQs over linear rules or CQs over guarded rules). These results have been published at IJCAI'17 [13].