nstraint will be enforced iff all literals listed here are true. </p>
<p>If this is empty, then the constraint will always be enforced. An enforced constraint must be satisfied, and an un-enforced one will simply be ignored.</p>
<p>This is also called half-reification. To have an equivalence between a literal and a constraint (full reification), one must add both a constraint (controlled by a literal l) and its negation (controlled by the negation of l).</p>
<p>Important: as of September 2018, only a few co