NOT.3:1 - Problem frame

Use this when a notation can form expressions, but its users lack a clear way to obtain the consequence those expressions are supposed to support. A legend may explain the signs while leaving the reader to invent how to combine, inspect or manipulate them.

Start with one question an expression should help answer. Give its relevant parts an interpretation, supply the operations needed to read them together, and follow that reading to a result. A useful first result can also be a located gap: a value, interpretation rule or reader capability that must be supplied before the question can be answered.

An operative interpretation here connects what an expression stands for with what a prepared reader can do to obtain a needed consequence from it. Reading can involve calculation, inspection of a diagram, rule-based manipulation or enactment. The reader may be a person or a computational agent; the applicable operations and preparation depend on that reader.

The designer needs the intended subject account and the operations on which the reading depends. The first example uses elementary Boolean reasoning, explained in the case; the temporal example uses addition and interval comparison. A machine implementation is a further construction when required.

Use an existing interpretation directly when it already supplies the needed reading. A.6.3.RT.OE addresses building an operative expression under an available scheme. Use the present method to develop or repair the scheme’s interpretation and its reading operations. NOT.2 addresses missing grouping, binding and connection rules.