  Common Knowledge Logic is meant to describe situations of the real world
where a group of agents is involved. These agents share knowledge and make
strong statements on the knowledge of the other agents (the so called
\emph{common knowledge}). But as we know, the real world changes and overall
information on what is known about the world changes as well. The changes are
described by dynamic logic. To describe knowledge changes, dynamic logic should
be combined with logic of common knowledge. In this paper we describe
experiments which we have made about the integration in a unique framework of
common knowledge logic and dynamic logic in the proof assistant \Coq. This
results in a set of fully checked proofs for readable statements. We describe
the framework and how a proof can be
