A.3.3.TR:4.1 - Choose the state, step and inputs

Name what changes and the observation or decision that depends on it. Recover the admitted states, using A.3.3.CC when their compatibility is still unresolved. Separate changing values, parameters held fixed and inputs supplied from outside the model.

Choose what counts as one step. A step can be one instruction, one transaction, an event, an observation interval or an interval of physical evolution. Say which intermediate effects the model retains. Declaring a read-and-write pair atomic is a substantive assumption about interference, as :5.1 shows.

Retain the values needed to apply the rule. A saved read and an instruction position can matter even when neither is visible in the final output. A mechanical law can require velocities as well as positions. If two cases described by the same retained values require different continuations under the same inputs, return to the state choice or retain the unresolved alternatives. A.3.3 supplies the prediction-sufficiency comparison.

For an interval of evolution, specify the inputs over that interval. One initial input value determines a later result only under an assumption such as a held input or a supplied input law. Distinguish that condition from the initial state.