Data complexity of answering conjunctive queries over SHIQ knowledge bases

In [6] the authors give an algorithm for answering conjunctive queries over ALCN R knowledge bases which is coNP in data complexity. Their technique is based on the tableau technique for checking sat-isfiability in ALCN R presented in [2]. In their algorithm, the blocking conditions of [2] are weakened in such a way that the set of models their algorithm yields suffices to check query entailment. The algorithm we propose consists on applying a similar technique to the tableaux algorithm in [4], which decides the satisfiability of SHIQ knowledge bases. As a result we have an algorithm for answering conjunctive queries over SHIQ knowledge bases that is also coNP in terms of data complexity.