# E91 protocol's error rate

E91 protocol detects the eavesdropper by using CHSH inequality. If the value of CHSH inequality is equal to 2sqrt(2), then there is no eve. On the other hand, if the value is between -sqrt(2) and sgrt(2), there is eve. The question is, if the value is neither between -sqrt(2) and sgrt(2) nor equal to 2sqrt(2), then what happens to the eve's presence.