B.5.FM:1 - Problem frame

Use this pattern when you need to reason about a situation or formal problem but do not yet have an account on which to perform the needed inference. You may know relevant laws, facts or techniques while still being unable to choose the participants, distinctions and relations that make them useful here.

Begin with what the answer should help you understand or do, the observations or formal rules already available, and enough subject knowledge to propose a relation. Construct a provisional model, obtain a consequence and use it to answer the question or locate the next missing contribution. A sketch and a limiting argument may provide that first result.

“First” means the first usable model for this question. An earlier model, an analogy or a specialist’s explanation can supply its starting material. Use an adequate existing model directly when construction is unnecessary. If an available concept is understood but its correspondence to the situation is missing, B.5.4 supplies that interpretation work. If the required inference needs subject knowledge you cannot recover, obtain that contribution.