public boolean checkCollisions(String operator) {
		if(operator.equals(AND))
			return true;
		else if(operator.equals(OR))
			return true;
		else if(operator.equals(IMPLY))
			return true;
		else if(operator.equals(DOUBLE_IMPLY))
			return true;
		else if(operator.equals(NEGATIVE))
			return true;
		else
			return false;
	}