a product of two functions, one of them related to particle 1 and the other related to particle 2, so that we can always think of such results as being clasically correlated. Next the authors examined a situation in which observer 3, independent of observers 1 and 2, performs spin measurements on particle 3 along direction $\vec{e}_3$. The results obtained by observer 3 are then used to classify the results of observers 1 and 2 into two distinct subensembles: whenever a result $+1$ ($-1$) is found for particle 3 in a particular run of the experiment, the corresponding results for particles 1 and 2 are assigned to subensemble $+$ ($-$). KZ demonstrated that an entanglement between particles 1 and 2 indeed occurs by showing that for certain measurement directions $\vec{e}_3$ the resulting correlation function $E^{+}_{12}$ ($E^{-}_{12}$) for subensemble $+$ ($-$) can yield a violation of Bell’s inequality. Since the degree of entanglement within either subensemble $+$ or $-$ depends on the measurement direction $\vec{e}_3$, and due to the fact that the spin measurements are carried out on the particles in spacelike separated regions, KZ came to the conclusion that the property of entanglement depends on the whole measurement context and 