public static Backbone compute(final Formula formula) {
        return compute(formula, formula.variables(), BackboneType.POSITIVE_AND_NEGATIVE);
    }
public static Backbone compute ( final Formula formula ) { return compute ( formula , formula . variables ( ) , BackboneType . POSITIVE_AND_NEGATIVE ) ; }
Computes the complete backbone for a given formula.
@param formula the given formula
@return the backbone or {@code null} if the formula is UNSAT