Bounded Proof Signoff: What a Depth Actually Proves: Software and Programmer View

Software and verification-program view

Coverage and waiver governance should integrate with simulation planning and release criteria.

What teams feel

• inconsistent formal outcomes across tool or config updates

• CI noise from vacuous passes and inconclusive aging

• traceability gaps between spec requirements and property IDs

Workflow and API impact

• assertion and checker naming standards for cross-team triage

• assumption ownership and change review policy

• trace and replay artifact retention expectations

Toolchain and automation implications

• engine strategy reproducibility across compute environments

• incremental rerun behavior under RTL churn

• automation for vacuity and coverage deltas

Mitigations

• enforce assumption-review templates with spec references

• fail CI on critical vacuity and stale-inconclusive thresholds

• standardize trace capture and minimal replay packaging

SOFTWARE VIEW - Bounded Proof Signoff: What a Depth Actually Proves
// gate promotion on non-vacuous closure and assumption audit stability

Formal deep dive

Signoff quality is requirement-centric and must integrate proof status, reachability, bounded limits, and waiver governance.

Concept diagram

FORMAL SIGNOFF PYRAMID

requirements -> properties and covers -> quality metrics -> waiver governance -> release decision

Metric graph

SIGNOFF CONFIDENCE TREND

fully proven critical    ███████
bounded-only critical    ████
unexplained cover gaps   ███

Metrics and artifacts to collect

• requirement-to-proof closure map

• critical cover reachability and gap aging

• bounded-only risk register

• waiver debt with owner and expiry

Mini case study

A release review blocked signoff until bounded-only properties were paired with explicit residual-risk and replay plans.

Debug branches

• Separate status color from proof quality dimensions.

• Treat unreachable critical covers as signoff blockers.

• Document bounded-horizon rationale with architecture limits.

Senior review question

Ask: which requirement intent is proven, under which assumptions, and what residual risk remains?

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.

Principal formal review addendum

Bounded Proof Signoff: What a Depth Actually Proves should be reviewed as a requirement-evidence workflow, not a single status report.

Use non-vacuous closure rate, counterexample turnaround time, and requirement-level residual risk trend as the monitoring lens and formal closure packet: assumptions audit, proof status matrix, counterexample classification, and requirement traceability as closure proof.

Signoff is requirement-centric evidence synthesis, not a single dashboard percentage. Strong teams preserve legal reachability while improving convergence.