  In this paper it is shown that no public announcement scheme that can be
modeled in Dynamic Epistemic Logic (DEL) can solve the Russian Cards Problem
(RCP) in one announcement. Since DEL is a general model for any public
announcement scheme we conclude that there exist no single announcement
solution to the RCP. The proof demonstrates the utility of DEL in proving lower
bounds for communication protocols. It is also shown that a general version of
RCP has no two announcement solution when the adversary has sufficiently large
number of cards.
