This Rational Rose file contains a suggested use case diagram and a class diagram for the problem.

Notes:

• The top level use case is quite simple.
• Choices should be modeled as a class, not an attribute.
• Multiple post times are possible for a voting problem.
• A derived variable, IsCurrent, is used as a quick way to indicate which voting problem is 'current'.

• Person(PersonId, FirstName, LastName, EMailAddress)
• Adminstrator(PersonId, AccountName, Password)
• PersonID is a foreign key of Person(PersonID).
• PersonID is a candidate key of Administrator.
• Alternatively, PersonID can be the primary key.
• Vote(VoteID, PersonID, VoteTime, IPAddress, ChoiceID, VotingProblemID)
• PersonID is a foreign key of Person(PersonID).
• ChoiceID is a foreign key of Choice(ChoiceID).
• VotingProblemID is a foreign key of VotingProblem(VotingProblemID).
• Comment(CommentID, VoteID, Description).
• Alternatively, Comment may be an attribute in Vote.
• VoteID is a foreign key of Vote(VoteID).
• VotingProblem(VotingProblemID, SetterID, SetDate, Question, IsCurrent)
• SetterID is a foreign key of Administrator(PersonID).
• Choice(ChoiceID, Order, Description, VotingProblemID)
• VotingProblemID is a foreign key of VotingProblem(VotingProblemID).
• Keyword(KeywordID, Name, Description)
• ProblemKeyword(VotingProblemID, KeywordID)
• VotingProblemID is a foreign key of VotingProblem(VotingProblemID).
• KeywordID is a foreign key of Keyword(KeywordID).
• PostTime(PostTimeID, StartTime, EndTime, VotingProblemID)
• VotingProblemID is a foreign key of VotingProblem(VotingProblemID).