C.43:4.1.3 - Describe incomplete and unsuitable arrangements without inventing missing parts
Start from the incumbent’s actual relations. An unexecuted command, a delayed observation, a response based on a stale assumption and competing local allocations can each explain a different failure. Retain the working contributions and recover the particular connection whose change could improve the receiving result. A globally unsuitable arrangement can contain useful local control.
| Existing arrangement | What the common account retains | What the next judgement needs |
|---|---|---|
| A fixed input over the present interval | The way the input was set, its execution and the expected response; later feedback can lie outside this interval | Whether disturbances and uncertainty permit this continuation until another decision |
| Feedback that amplifies an unwanted deviation | The obtaining observation-to-action relation and its actual dynamics | A change of rule, sign, gain, delay or means whose consequences improve the relevant behavior |
| Several local controllers with conflicting demands | Each local rule, available information and actual influence | A feasible joint allocation, agreement or changed demand, rather than an assumed central chooser |
| A proposed action with no available means or authority | A recommendation or selected proposal and the missing realization relation | How to obtain the means or agreement, change the proposal, or state the remaining inability to act |
| An unexplained gap in the observed arrangement | The supported relation and the uncertainty about another contribution | An observation or source that can distinguish absence from an omitted description |
A mathematically degenerate case is useful when the mapping is justified: a constant policy removes dependence on new observations; a zero coupling removes a specified influence. A missing observation in the evidence is not such a zero. Likewise, a coupled nonlinear arrangement need not be a limiting case of one particular linear model to be describable here. Use the common relations to select an adequate subject model under C.29, then establish its relevant behavior. This preserves both an honest description of imperfect control and the stronger question of what should replace it.