To impose a harder constraint on model building, one might want to close a cycle. Until now, such a construction was not possible with mcsym: no cycle where permitted in the construction order. With the addition of the relation constraint a modelisator can close a cycle with this new constraint.
Be aware that the constraint should be used only when you cannot build a relation via the pair (not adjacent) / connect (adjacent) statements. Both do the same thing but the pair and connect statements reduce the search space before exploration, which is much less costly than using the relation constraint.
relation (<relationConstraint>+)
| <relationConstraint> | = | <res1> <res2> <properties> |
Example:
relation
(
42 43 { stack }
41 42 { stack }
40 41 { stack }
39 40 { stack }
)
|