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# all_disjoint(+SetVars)

All sets disjointness global constraint
*SetVars*
- A list of set variables.

## Description

Constrain all pairs of sets in SetVars to be disjoint. I.e. No two sets
can have a common element (empty pairwise intersection).
This version of all_disjoint/1 is a weak global constraint, but stronger
than the simple posting of all pairwise disjoint/2 constraints, since
it posts the additional constraint that the sum of the cardinalities of
SetVars must be less than or equal to the cardinality of the union of all
the initial LUBs.

### Fail Conditions

Fails if SetVars can not be all disjoint.
### Resatisfiable

No.
## Examples

?- all_disjoint([[7],[8],[i,k]]).
yes
?- all_disjoint([[7,8],[i],[8]]).
no
?- sets([X,Y,Z], [],[1,2,7,8,9], [cardinality:2]), all_disjoint([X,Y,Z]).
no
?- sets([X,Y,Z], [],[1,2,7,8,9], [cardinality:2]), all_disjoint([X,Y,Z]), 2 `@ X, lub(Y,LubY), lub(Z,LubZ)
LubY = [1,7,8,9], LubZ = [1,7,8,9]

## See Also

`$ / 2, `<> / 2, complement / 2, complement / 3, `/= / 2, all_union / 2