My research interest is in the investigation of the essence of rationality and knowledge and its application to artificial intelligence. We mainly investigate how a rational agent acquires knowledge, represents the knowledge by logic, and acts and makes decisions based on logical reasoning. In particular, our most interesting topic is the rationality criteria of logical reasoning under the environment of incomplete and insufficient information.

        Technically, a major part of our work involves the study of properties of different types of logic for uncertain reasoning, for example, fuzzy logic, possibilistic logic, modal logic, conditional logic, nonmonotonic logic, etc. Furthermore, we have also developed some uniform frameworks for these different types of logic.

        Recently, we have also concentrated on the formalization of the logical properties of intelligent agents. Based on different logical systems like epistemic reasoning, deontic reasoning, preferential reasoning, etc., we can discuss some characteristic features of intelligent agents.