Scenario: Over-Constraint Creates False Confidence - Interview Scenario

Scenario

A safety property appears proven quickly after environment constraints were updated. Later simulation exposes a bug in a legal traffic mode that formal never explored.

OBSERVED METRIC
Proof status improves while legal-mode cover reachability drops and assumption influence increases sharply.

45-MINUTE INTERVIEW FLOW
0-5: define requirement and KPI
5-15: classify first divergence boundary
15-25: identify proving artifact packet
25-35: propose bounded fix with owner
35-45: define validation matrix and rollback

Common traps to avoid

• Treating improved proof runtime as proof-quality improvement.

• Not tracking assumption-to-spec traceability in review packets.

• Ignoring failed cover goals that indicate blocked legal behavior.

Scenario debrief

Score scenario responses on assumption discipline, first-divergence analysis, proof-quality evidence, and release-safe mitigation.

requirements -> model -> proof status -> closure decision

closure confidence trend by risk tier

Debrief prompts

1. Which requirement failed first, and is that path legally reachable?

2. Which modeling assumption most influences this result?

3. What smallest reversible action improves confidence without hiding legal behavior?

Key takeaways

• Tie each proof claim to assumption boundaries and reachability evidence.

• Prefer minimal reversible fixes and preserve legal behavior visibility.

Common pitfalls

• Treating runtime reduction as proof-quality improvement without audits.

• Declaring closure while critical covers remain unreachable.

• Using broad waivers instead of first-divergence root-cause ownership.