Problems and Frames
Serving or helping to find out or discover;
But connotations of trial and error.
Identify the core problem
Identify the ancillary problems
Standard decompositions of sub problems
Identify concerns and difficulties
More than two moods
Complex domain or requirement
Modelling the user
When one part of your problem is in a slow tempo and one in a fast tempo, treat them as different sub problems.
Look at Tennis Court Lights handout
What are the different tempi?
More than two moods
Every frame has at least 1 description (of domain properties) in the indicative mood
And at least two (req. and spec.) in the optative mood.
Sometimes you need 3 moods which indicates presence of at least two subproblems
Look at Air Traffic Control
Complex domain or environment
In each basic frame a clear expectation of relative complexities of the domains and requirement complexity
Req. Beh. Frame: controlled domain may be complex, but you expect the requirement to be satisfiable by simple control law.
Commanded Beh. Frame: Controlled domain complex, but controller simple.
Info. Display Frame: RW complex, display domain quite simple. Req. = simple relationship between req and specification phenomena of RW
Workpieces: w/pieces may be complex, user domain simple
Transformation: inputs & outputs of roughly equal complexity. I/O relation satisfiable by traversal of both domains
An unusually complex domain indicates a possible further decomposition
Package router: core problem was Required Behaviour.
Complexity = destinations not available to sensors, so introduce a model domain = new subproblem
In workpieces frame, user domain is unstructured stream of commands
Where user domain is of interest for its own sake, this indicates a subproblem
If we need to know who edited a workpiece, we need a model of each user to record individual editing activities. This is a separate problem
What are the different tempi in the Home Heating Control problem?
What are the moods in the Package Router problem?
What are the subproblems in the University Administration system?