Cone of Influence (COI): State-Space Reduction with Intent Preservation: Step-by-Step Walkthrough

Step-by-step analysis walkthrough

Use this sequence when owning Cone of Influence (COI): State-Space Reduction with Intent Preservation in a formal review.

1. Confirm trigger reachability and non-vacuous evaluation.

2. Inspect first-cycle divergence and classify failure source.

3. Check reset/fairness/assumption interactions before editing RTL.

4. Apply smallest reversible fix in model or implementation.

5. Re-run sibling properties and cover goals for collateral impact.

6. Archive decision with owner and residual-risk statement.

Artifacts to collect

• formal closure packet: assumptions audit, proof status matrix, counterexample classification, and requirement traceability

• counterexample replay package

• assumption traceability matrix

• vacuity and cover dashboard snapshot

• post-fix closure trend report

Decision memo template

FORMAL DECISION MEMO - Cone of Influence (COI): State-Space Reduction with Intent Preservation
symptom:
classification:
root cause:
fix:
validation:
owners: formal verification owner, rtl owner, verification lead

Formal deep dive

FPV foundations are reliable only when assumptions, reset semantics, and requirement intent are explicitly modeled and audited.

Concept diagram

FPV FOUNDATION LOOP

requirements -> property set -> assumptions and reset model -> prove/fail traces -> closure audit

Metric graph

FOUNDATION HEALTH

vacuous passes         ████
reachable proofs       ███████
inconclusive backlog   █████
reopened properties    ███

Metrics and artifacts to collect

• assumption traceability matrix

• vacuity and reachability status

• proof core relevance summary

• counterexample classification trend

Mini case study

A green-looking run was invalidated after legal-mode covers failed, exposing assumptions that removed realistic traffic.

Debug branches

• Validate requirement-to-property mapping before tuning runtime.

• Check legal scenario reachability after every assumption change.

• Classify first divergence as model issue or RTL bug.

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

Cone of Influence (COI): State-Space Reduction with Intent Preservation 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.

Formal foundations are strongest when assumptions, reset semantics, and requirement intent are all explicit and reviewable. Strong teams preserve legal reachability while improving convergence.