G. Peruzzi et A. Rimini, INCOMPATIBLE AND CONTRADICTORY RETRODICTIONS IN THE HISTORY APPROACH TO QUANTUM-MECHANICS, Foundations of physics letters, 11(2), 1998, pp. 201-207
We illustrate two simple spin examples which show that in the consiste
nt histories approach to quantum mechanics one can retrodict with cert
ainty incompatible or contradictory propositions corresponding to non-
orthogonal or, respectively, orthogonal projections.