“…D-posets have been introduced in [20] in order to model events in quantum probability. They generalize Boolean algebras, MV-algebras and other probability domains, and provide a category in which observables and states become morphisms [2], [11]. Recall that a D-poset is a partially ordered set with the greatest element 1 X , the least element 0 X , and a partial binary operation called difference, such that a b is defined iff b ≤ a, and the following axioms are assumed: [16], [17], i.e., systems X ⊆ I X carrying the coordinatewise partial order, coordinatewise convergence of sequences, containing the top and bottom elements of I X , and closed with respect to the partial operation difference defined coordinatewise.…”