Coffman--Kundu--Wootters inequality ($C_{A:BC}^2\ge C_{AB}^2+C_{AC}^2$)

For a pure state of three qubits, the squared concurrence obeys $C_{A:BC}^2\ge C_{AB}^2+C_{AC}^2$. In particular, if $A$ and $B$ form a maximally entangled pair, then $A$ has no entanglement with $C$.