Any n-qubit state with n independent perfect correlations is equivalent to a
graph state. We present the optimal Bell inequalities for perfect correlations
and maximal violation for all classes of graph states with n < 7 qubits. Twelve
of them were previously unknown and four give the same violation as the
Greenberger-Horne-Zeilinger state, although the corresponding states are more
resistant to decoherence.Comment: REVTeX4, 5 pages, 1 figur