public SortedSet < Literal > getCompleteBackbone ( ) { final SortedSet < Literal > completeBackbone = new TreeSet <> ( ) ; if ( hasPositiveBackboneResult ( ) ) { completeBackbone . addAll ( this . positiveBackbone ) ; } if ( hasNegativeBackboneResult ( ) ) { for ( final Variable var : this . negativeBackbone ) { completeBackbone . add ( var . negate ( ) ) ; } } return Collections . unmodifiableSortedSet ( completeBackbone ) ; }
Returns all literals of the backbone . Positive backbone variables have positive polarity negative backbone variables have negative polarity .