Logic Exercises

Imagine that you are a policy analyst and you are given the following natural language policies.

Exercise 1: PKI Computer System use policy

Convert the following into logic, then state a violation case.

Policy Natural Language Text

Acceptable Computer use in PKI

• Users must have approved account credentials to log in to a system.
• Only students and faculty that work in or attend classes in PKI should have approved credentials.
• Authenticated users must not leave the systems they access unlocked and unattended when logged in. All systems should have an auto lock feature that locks the system after 5 minutes of inactivity when a user is authenticated.

Tasks

Work as a group to:

• State the Policy using first-order logic
• Identify a single violation and state it formally

Exercise 2: Student Account non-repudiation policy

Convert the following into logic, then state a violation case.

Student account non-repudiation and logging

• All student account transactions must be logged and stored for 7 years.
• Transaction logs must include, at a minimum, the time when the transaction occured, the location and name of the on-campus vendor where the transaction occured, the total cost of the transaction, and the id of the point of sale system that the transaction occurred on.

Tasks

Work as a group to:

• State the Policy using first-order logic
• Identify a single violation and state it formally

Hint

This one is much harder than the first one. Note that you can nest quantifiers. Also be sure to properly quantify all variables.

Exercise 3: “flip it and reverse it” (ti esrever dna ti pilf)

Task

Translate the following formal logic statement into natural language as it is stated formally AND as it might be listed in a real policy. Be explicit. What kind of policy category might this statement fit into?

Statement