SYSE.50:4.3 - Construct the rule and its fallback

Relate the available signal to qualified outcomes, then select a decision rule under the receiving loss and resource constraints. For a threshold rule, compare supported continuation and assistance outcomes on calibration cases across candidate thresholds. Inspect unsupported continuation and unnecessary help separately, including the delay or cost of obtaining that help. A favorable average is insufficient when a protected error exceeds the declared allowance.

A set-valued construction is another option: score the allowed candidate actions and calibrate which remain plausible under the source method’s assumptions. One supported candidate can permit selection; several consequentially different candidates can trigger clarification. An empty or inapplicable set needs an explicit fallback. A probability or coverage claim requires the corresponding sampling, labeling and calibration basis; a hand-chosen cutoff is an engineering rule until such evidence exists.

Make the output implementable: response, target question or source, decisive grounds, applicability and stop condition. Keep required facts, permissions and effect recovery as independent conditions. No confidence value authorizes replay of an attempt whose effect remains unknown.

Define behavior outside qualification. A changed performer/model condition, inaccessible signal, unrecognized input or defeated calibration premise can return to an adequate direct rule, request the specific missing contribution, or stop with the exact gap. It must not silently become permission to guess.