CAD.5:4.8 - Compare whole alternatives and return to the failed dependence

For each serious channel-and-schedule alternative, obtain the information update, its cost and delay, the error bound and the control conclusion. Keep the demanded behavior, initialization and resource accounting the same. Compare the alternatives that meet the demand; distinguish a proof of impossibility from failure of a sufficient bound.

Choose a sufficient arrangement with an explained cost and margin. A comparison can establish the best member of a stated finite family only when the objective is comparable and every potentially better member is evaluated decisively. Otherwise return the best qualified member found and the unresolved alternatives. A stochastic design can instead minimize an explicitly selected expected cost, but its covariance or a finite successful simulation is not a deterministic bound for this method’s hard constraints.

Return according to what failed:

Observed failure	Useful design return
Two compatible histories need different actions before any distinguishing packet arrives	Change what is observed, the sampling or delivery time, the actuator or the required behavior. Extra computation on the same information cannot distinguish them.
A feasible set is too large only after coarse approximation	Retain a useful correlation or use a tighter representation; include its execution cost.
Estimation uncertainty fits, but the given feedback violates an input limit	Change or requalify the feedback and its continuation, or change the physical limit or demand. Do not label this a sensor impossibility.
A longer observation gap or shared-resource delay breaks the bound	Restore a qualified timing arrangement or recalculate the information and control sets for the changed timing.
A stable unobserved component fits the task without intervention	Remove an unnecessary channel and its associated internal history.
A mode switch changes the permitted error or invariant set	Prove that the actual state and information representation enter the new qualified set, or retain a common valid bound. Nominal mode labels do not establish this.