Superkey (Databases)

The Superkey of relation $R$ is a set of attributes $SK$ of $R$ with the following conditions:

• no two tuples in any valid relation state $r(R)$ will have the same value for $SK$ for any distinct tuples $t_1$ and $t_2$ in $r(R)$, $t_1[SK]\ne t_2[SK]$.
• this condition must hold in any valid state $r(R)$