Ahmetaj, Shqiponja2021-04-232021-04-2320202020http://dx.doi.org/10.1007/s13218-020-00671-whttps://dl.gi.de/handle/20.500.12116/36328A most promising approach to answering queries in ontology-based data access (OBDA) is through query rewriting. In this paper we present novel rewriting approaches for several extensions of OBDA. The goal is to understand their relative expressiveness and to pave the way for efficient query answering algorithms.Text/Journal Article10.1007/s13218-020-00671-w1610-1987