C.28.MR:4.2 - Recover the model that gives the replacement meaning

Write or recover each relevant mechanism in a form such as X_i = f_i(parents, U). The function tells how the modeled quantity is determined by other modeled quantities and by U, the inputs left outside these mechanisms. Recover their domains and the joint distribution of U, or their given values for a deterministic calculation.

Keep the subject interpretation with the equations. An equation’s left-hand side is selected by the causal account. Algebraically rearranging I=V/R to V=IR preserves the equality but does not decide which physical component an intervention replaces. In :5.2 the supply controls V and the resistor relates V to I.

Preserve common inputs and their dependence. If two disturbances arise from one shared event, retain that event or their joint law when calculating both effects. A simulation must generate one compatible joint input for a case; independent resampling of its components would change the model.

Recover only the mechanisms needed to determine the queried consequence and their relevant conditions. A missing actuator relation may prevent a physical consequence while still allowing a useful comparison inside an explicitly assumed model. State that assumption where the result uses it.