in the scenario proposed by bell (a bell scenario), two experimentalists, alice and bob, conduct experiments in separate labs. at each run, alice (bob) conducts an experiment formula_11 formula_12 in her (his) lab, obtaining outcome formula_13 formula_14. if alice and bob repeat their experiments several times, then they can estimate the probabilities formula_15, namely, the probability that alice and bob respectively observe the results formula_16 when they respectively conduct the experiments x,y. in the following, each such set of probabilities formula_17 will be denoted by just formula_15. in the quantum nonlocality slang, formula_15 is termed a box.