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# refine(?Svar)

Instanciate Svar to a value in its set domain.

?Svar
  A set domain variable or a ground set.

## Description

If Svar is a set domain variable, it labels Svar to its first possible value (which satisfies the constraints) by taking the largest possible set of elements chosen from the smallest one to the biggest one. If there are several possible instances of Svar, it creates choice points. It backtracks on the element taken. If Svar is a ground set, nothing happens. Otherwise it fails. If List is a possible list of set domain variables occuring in the program, the simplest labeling procedure is:

                labelings([]).
                labelings([S | List]) :-
                     refine(S),
                     labelings(List).

### Fail Conditions

Fails if Svar is not a set domain variable or ground set.

### Resatisfiable

On the taken elements.

## Examples

    [eclipse 21]: S `:: {} ..{1,2,5,3,8}, refine(S).

    S = {1, 2, 3, 5, 8}     More? (;)
    yes

## See Also

`:: / 2