Dynamic Epistemic Logic Incorporated With Group Knowledge

Dynamic epistemic logic (DEL) is a relatively new field of research in recent years. It aims to provide formal means of analysis of information change. Group knowledge is very important in DEL, for most of the effects and the interaction of the agents depends on their group knowledge.Group knowledge includes common knowledge and group implicit knowledge. Up to now, a DEL system incorporated with the two kinds of group knowledge has not been established yet. In this dissertation I aim to set up two DEL systems with the two kinds of group knowledge.By use of the reduction method we can get a sound and complete DEL system easily. This method can not only make the proof the completeness easier but also make the transformation from the static to the dynamic more perspicuous. But as for the usual common knowledge, the reduction method will no longer be available.In this dissertation I introduce the concept of relativized common Knowledge, which is proposed by B Kooi and J van Benthem in 2004. By giving the corresponding reduction axioms about relativized common Knowledge and group implicit knowledge, I set up two DEL systems with relativized common Knowledge and group implicit knowledge through the reduction method .In chapter 4, on basis of the system S5_m(C, D, E), which is established by van der Hoek and J -J Ch Meyer in 1996, I consider the relativized common Knowledge instead of the usual common knowledge and generalize the group notion in the group knowledge and then construct a new logical system S5_m~B(RC, D, E) as a base of the subsequent DEL systems. However, the usual canonical model for this system...