DTM.9:4.2 - Choose the response state and time description

Represent formation, decay, persistence and capacity limits at the resolution needed by the question. A response may depend on current activity, past experience or prediction. Use a state or history sufficient to represent that dependence.

An algebraic response a=F(x,u) assumes that its adjustment is sufficiently fast for the receiving result, where x describes relevant activity and u the proposed change. A simple dynamic alternative is:

τa' = F(x,u) − a, with τ > 0.

This illustrative first-order adjustment does not automatically represent learning, saturation or several kinds of memory. Introduce those relations only where supported. MMP.11/.18 govern the state choice and any reduction.

Test the simplification against the decision. A stationary comparison can tolerate a reduction that would be unsuitable for startup, short disturbances or a deadline. Even a fast response can matter when a brief transient crosses an irreversible boundary.