My research topic is located in the field of Artificial Intelligence (AI), in particular on the Semantic Reasoning part of AI. My principal focus is on developing a formal and comprehensive methodology for a new way of producing, publishing, maintaining, accessing and exploiting Open Data. The basic idea is that the Ontology-based Data Access (OBDA) paradigm can provide a formal basis for a principled approach to publish high-quality, semantically annotated Open Data. In the context of OBDA, I have also been investigating the problem of adding forms of inequalities to unions of conjunctive queries (UCQs), arguably the most popular class of queries for both database and ontologies. In particular, my focus on this topic is how inequalities affect the computational complexity of query answering over lightweight ontologies. Furthermore, I have also been studying (starting from my PhD long stay visiting period at University of Oxford) an extension of the recently proposed bag semantics for OBDA to deal with functionality axioms, too.