  Our objective is to extend the standard results of preservation and
reflection of properties by bisimulations to the coalgebraic setting, as well
as to study under what conditions these results hold for simulations. The
notion of bisimulation is the classical one, while for simulations we use that
proposed by Hughes and Jacobs. As for properties, we start by using a
generalization of linear temporal logic to arbitrary coalgebras suggested by
Jacobs, and then an extension by Kurtz which includes atomic propositions too.
