  For the classical mind, quantum mechanics is boggling enough; nevertheless
more bizarre behavior could be imagined, thereby concentrating on propositional
structures (empirical logics) that transcend the quantum domain. One can also
consistently suppose predictions and probabilities which are neither classical
nor quantum, but which are subject to subclassicality; that is, the additivity
of probabilities for mutually exclusive, co-measurable observables, as
formalized by admissibility rules and frame functions.
