4. Can a database contain two identical records without a negative effect on the integrity of the database? Why or why not? 9. Disclosure of the sum of all financial aid for students in Smith dorm is not sensitive because no individual student is associated with an amount. Similarly, a list of names of students receiving financial aid is not sensitive because no amounts are specified. However, the combination of these two lists reveals the amount for an individual student if only one student in Smith dorm receives aid. What computation would a database management system have to perform in order to determine that the list of names might reveal sensitive data? What records would the database management system have to maintain on what different users know in order to determine that the list of names might reveal sensitive data? 11. The response "sensitive value; response suppressed" is itself a disclosure. Suggest a manner in which a database management system could suppress responses that reveal sensitive information without disclosing that the responses to certain queries are sensitive. 12. Cite a situation in which the sensitivity of an aggregate is greater than that of its constituent values. Cite a situation in which the sensitivity of an aggregate is less than that of its constituent values. (Think about situations where knowing the aggregate of some information could infer some details and vice versa.)