6.9.3 FS Selection Constraint

The selection constraint exists also in a version where the sequence contains only FS variables. It is exported on feature fs of module Select:

X={Select.fs [X1 ... Xn] I}

Again the information about X can be improved by propagation. The upper bound of X is at most the union of the upper bounds of the Xis for i in the domain of I. The lower bound of X is at least the intersection of the lower bounds of the Xis for i in the domain of I. In other words, if $I\in D$ and $D_i\subseteq X_i\subseteq D_i'$ , then:

$\bigcap\limits_{i\in D} D_i\subseteq X\subseteq \bigcup\limits_{i\in D} D_i'$