after informing myself about how Cardano is working, I still have some (maybe silly) questions about some details:
Which type of Ouroboros is Cardano running at the moment? I think that Byron is running the classical one and Shelly is running Praos or Genesis, but I am not sure.
How Cardano is dealing with the nothing-at-stake problem? In genesis, this problem comes from the fact that multiple nodes can be elected as leader in a particular slot. So, how we deal with that? In this case, a fork would be produced and there is no reason to avoid forging over both blocks. Hence, a permanent fork would be produced.
The Chain Selection rule does not help to prevent the previous particualr problem.