I am starting this B thread for people to discuss and learn from. In particular, I am hoping it will help to clarify some of the confusing issues which have come up in the "CFD - Counterfactual Definiteness" thread. "Well wishings to ALL, for a complete and successful understanding!" _______________________ _______________________ The example below is due to Hardy. ______ Each of the instruments of Alice and Bob (which together perform a joint-entanglement-measurement at spacelike separation) have two settings, 1 and 2, for which the outcomes can be YES or NO. There is a quantum-mechanical entanglement scenario for which each of the following statements is true: (0) For the configuration <a1,b1>: the outcome (NO,NO) is sometimes obtained. (1) For the configuration <a1,b2>: if a1 gives NO, then b2 gives YES with certainty. (2) For the configuration <a2,b1>: if b1 gives NO, then a2 gives YES with certainty. (3) For the configuration <a2,b2>: the outcome (YES,YES) is forbidden. ______ I have taken this example (but adapted the notation) from Penrose's "Road to Reality", §23.5, p. 590. There, he mentions that the (NO,NO) outcome for the setting in (0) is obtained with a probability of 1/12.