Power pitfalls

OverviewBoundariesCorpus formsPitfalls

1. No exercise — no effect

A power with no exercise fact in the case answers NEITHER, and this is not a package defect (the two-step scheme). Diagnostics: no issue (the position is ACTIVE, there is no effect). Detection: check the assert of the exercise fact in given. Fix: add the exercise fact.

2. Exercise without valid_when — POWER_INVALID_EXERCISE

An exercise fact with unestablished valid_when: no effect + issue POWER_INVALID_EXERCISE (info). Detection: the document’s issues. Fix: establish the ground, or admit there was no exercise.

3. Conjunction in valid_when without parentheses

valid_when a and b; — LDC-E0201 (“expected ;”) plus LDC-E1305 on an unknown field; compilation fails. Write valid_when (a and b);. Detection: law engine check.

4. A judge in valid_when reads as a request, not a refusal

A judgment relation in valid_when gives NEITHER + REQUIRES_JUDGMENT + JudgmentRequest; no POWER_INVALID_EXERCISE is issued then. The mistake is reading NEITHER as “the power is invalid”. Check evaluation_status. If the effect is already locked by immunity, the judge is not asked.

5. Traps for automated authors

• _ in valid_when passes check, but the effect materializes silently never: the power is ACTIVE, the exercise attempt is only info POWER_INVALID_EXERCISE, the effect is NEITHER (a known open gap). Bind the variable with the rule body.
• An undefeated power/immunity pair: truth_status NEITHER, but evaluation_status UNRESOLVED_NORMATIVE_CONFLICT in examples/power-immunity/. Do not confuse the result status with the truth status.
• A power effect is invisible to a same-round defeater (a known open remainder): an unless condition reading an effect-reachable predicate silently does not fire. Write the defeater over a raw case fact.
• subject does not affect the status: its absence/presence never changes the engine’s answer.
• Diagnostic LDC-E1305 names each missing one of the four fields separately — read the whole list, not the first.