DL-Lite with role inclusions

We analyse DL-Lite logics with role inclusions and present a complete classification of the trade-off between their expressiveness and computational complexity. In particular, we show that in logics with role inclusions the data complexity of instance checking becomes P-hard in the presence of functionality constraints, and coNP-hard if arbitrary number restrictions are allowed, even with a very primitive form of concept inclusions. Moreover, the combined complexity of satisfiability in this case jumps to ExpTime. On the positive side, it turns out that the combined complexity for the logics without number restrictions depends only on the form of concept inclusions and can range from NLogSpace and P to NP; the data complexity for such logics stays in LogSpace.