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# el_weight(+Var, ?Wvar)

Var is an element of type e(Val,Weight) from a weighted domain. Wvar is a free variable unifying with the weight Weight of Var.

+Var
  A weighted element.
?Wvar
  Term unifying with an integer.

## Description

Unifyes the weight of the term Var which should be of the form e(Val,Weight) with Wvar. This predicate is convenient to select elements for the labeling of weighted sets.

### Fail Conditions

Fails if Var is not of the form e(Val,Weight) or if Wvar is not unifyable with the weight.

### Resatisfiable

No.

## Examples

    [eclipse 12]: E = e(1,2), el_weight(E, W).

    E = e(1, 2)
    W = 2
    yes.

## See Also

max_weight / 2, `:: / 2