@Override
	public boolean equals(Object obj) {
		if (this == obj)
			return true;
		if (obj == null)
			return false;
		if (getClass() != obj.getClass())
			return false;
		PeriodHardConstraint other = (PeriodHardConstraint) obj;
		if (constraint != other.constraint)
			return false;
		if (e1Id != other.e1Id)
			return false;
		if (e2Id != other.e2Id)
			return false;
		return true;
	}