My research is in the subject of inconsistent knowledge. This is an increasingly important topic in many areas of computer science including artificial intelligence, robotics, natural language processing, databases, information systems, and software engineering. Inconsistency is omnipresent in the world. So we need to design systems that can address the problems and the opportunities raised by the widespread existence of inconsistency. By better understanding the nature of inconsistency, in particular by developing formal theories of inconsistency in knowledge, we can tackle these challenges. This raises the need to develop ways to analyse and characterise different kinds of inconsistency, to develop ways to reason in the presence of inconsistency, to develop ways to respond to inconsistency, and if necessary to resolve inconsistency, to develop ways to merge inconsistent knowledge from heterogeneous sources, and to construct arguments (pros and cons) for inferences using inconsistent knowledge. My work is based on formal propositional and predicate logic and it is published primarily in the area of knowledge representation and reasoning, which is a branch of artificial intelligence, and data and knowledge engineering.