Bell's theorem for general N-qubit states

A single general Bell inequality was derived which was a sufficient and necessary condition for the correlation function for N particles described in a local and realistic picture. The measurements on each particle could be chosen between two arbitrary dichotomic observables. A condition for an arbitrary N-qubit mixed state was also derived to violate this inequality. The condition obtained was a generalization and reformulation of the Horodecki family condition for two qubits.