Problem 1
Explain when it may be cost effective to use formal specification and verification in the development of safety-critical software systems. Why do you think that critical systems engineers are against the use of formal methods?
Problem 3
Explain why it is practically impossible to validate reliability specifications when these are expressed in terms of a very small number of failures over the total lifetime of a system.
Problem 4
Explain why ensuring system reliability is not a guarantee of system safety.
Problem 5
Using examples, explain why security testing is a very difficult process.
Problem 6
Suggest how you would go about validating a password protection system for an application that you have developed. Explain the function of any tools that you think may be useful.
Problem 8
List four types of systems that may require software safety cases, explaining why safety cases are required.
Problem 10
Assume you were part of a team that developed software for a chemical plant, which failed, causing a serious pollution incident. Your boss is interviewed on television and states that the validation process is comprehensive and that there are no faults in the software. She asserts that the problems must be due to poor operational procedures. A newspaper approaches you for your opinion. Discuss how you should handle such an interview.
