Preservation in Dynamic Epistemic Logic

This article examines the preservation of structural properties in epistemic and doxastic logic, with a particular focus on action model logic and the dynamics of group belief. Two central questions guide the analysis: (a) which frame conditions remain invariant under the execution of epistemic actions? and (b) do group conditions—properties allowing groups to be modeled as unified agents—persist after such actions? The study further explores specific subclasses of epistemic actions, including public announcements and unconditional actions, highlighting their distinctive preservation features. These findings contribute to a deeper understanding of the logical foundations of epistemic and doxastic reasoning, particularly within dynamic multi-agent frameworks.