On Query Answering in Description Logics with Number Restrictions on Transitive Roles.

We study query answering in the description logic SQ supportingnumber restrictions on both transitive and non-transitive roles.Our main contributions are (i) a tree-like model property for SQ knowledgebases and, building upon this, (ii) an automata based decisionprocedure for answering two-way regular path queries, which gives a3ExpTime upper bound.