After proving correspondence theorems between syntactic and semantic proper
ties of a Kripke Structure, these properties are combined in order to gener
ate two polar semantic structures, that is, partitions and nestings. Then,
the relevant properties are extended to Probabilistic Kripke Structures and
the concept of a Mixed Knowledge Hierarchy is introduced and associated wi
th two dual measures of events. Finally, an application to Decision Theory
is provided for the particular case of a 2-level hierarchy. (C) 1999 Elsevi
er Science S.A. All rights reserved.