public static boolean isInc(List<ObjFunc> ofs) {
        if (ofs.isEmpty()) {
            throw new IllegalArgumentException("No Objective function(s) defined. ");
        }
        boolean inc = ofs.get(0).getOF().positiveDirection();
        for (ObjFunc of : ofs) {
            if (of.getOF().positiveDirection() != inc) {
                throw new IllegalArgumentException("Objective function(s) optimization direction mismatch!");
            }
        }
        return inc;
    }