B.5.QD.CF:1 - Problem frame

Use this when an account makes needed outcomes appear incompatible and you need to find what could change without losing the purpose of the work. Two requirements may concern different operating conditions, yet the model gives them one setting. A familiar means of obtaining one result may obstruct another result, although that means has never been shown necessary.

First useful move. Put the two demands beside the statement that makes them conflict. Ask what requires that statement. For example, “the setting must be at least 6 during work and at most 2 during quiet operation” conflicts with a fixed-setting design. It leaves open a question about changing the setting between those conditions.

The result is a reformulated question or candidate construction whose retained requirements, changed premise and remaining obstacle are understood. Sometimes the useful result is an impossibility under the retained conditions, followed by a decision about which requirement can change.

The reader needs enough knowledge to interpret the requirements and the inference connecting them, or access to someone who can supply that interpretation. Start with ordinary statements and a small case. Use an adequate existing solution directly. If the only unresolved question is choosing an accepted trade-off, compare the options; recovering premises is useful when it could reveal another option or change the grounds for that choice.