Two Upper Bounds for Conjunctive Query Answering in SHIQ

We have shown recently that, in extensions of ALC that involve inverse roles, conjunctive query answering is harder than satisfiability: it is 2-ExpTime-complete in general and NExpTime-hard if queries are connected and contain at least one answer variable [9]. In this paper, we show that, in SHIQ without inverse roles (and without transitive roles in the query), conjunctive query answering is only ExpTime-complete and thus not harder than satisfiability. We also show that the NExpTime-lower bound from [9] is tight.

• Type: Conference
• Year: 2008
• Where: DLOG
• Authors: Carsten Lutz
• Keywords: Automated Reasoning, Conjunctive Query Answering, DLOG 2008, Inverse Roles, Transitive Roles