4.2.2.7. Set-related constraints

In this section: disjoint, partition_set, roots.

disjoint

predicate disjoint(var set of $$E: s, var set of $$E: t)

Requires that sets s and t do not intersect.

partition_set

predicate partition_set(array [$X] of var set of $$E: xs,
                        set of $$E: universe)

Constrains the sets in array xs to partition the universe.

roots

1.  predicate roots(array [$$X] of var $$Y: xs,
                    var set of $$X: preimage,
                    var set of $$Y: image)

2.  function var set of $$X: roots(array [$$X] of var $$Y: xs,
                                   var set of $$Y: image)

Requires that xs[i] in image for all i in preimage, i.e. preimage is the set of indices i for which xs[i] is in image.
Returns the set of indices i such that xs[i] is in image.