An open logic system

A theory of open logic is developed. It can be used to describe the growth and the modification of knowledge, and to express the evolution of a hypothesis. Some concepts, such as new premise, rejection by facts, reconstruction of a hypothesis and epistemic process are defined. Their properties are studied and the related theorems are proved. The concept of the limit of an epistemic process is further defined. Every empirical model about a specific problem is proved to be the limit of an epistemic process. As an application of the theory, a model theory of Reiter's default reasoning is given using the concepts of open logic.