# Formal Methods Guide

> Provide reference knowledge on VDM-SL and formal methods. Triggered by "VDM-SL syntax", "how to write types", "what is a pre-condition", "what is an invariant", "meaning of proof obligations", "what are formal methods", or "formal specification". Also responds to Japanese: 「VDM-SLの文法」「事前条件とは」「形式手法とは」等。 Referenced as background knowledge by other skills (define-contract, verify-spec).

## Facts
- Page: https://tashan.sh/capability/skill-kotaroyamame-formal-methods-guide
- tashan id: skill:kotaroyamame/formal-methods-guide
- Source: https://github.com/kotaroyamame/formal-agent-contracts
- Type: skill
- Category: devtools
- tashan score: not scored (catalogued only — too little public evidence)
- Adoption: 9.0
- Upkeep: 93.0
- Freshness: 84.0
- Evidence coverage: 84% of the inputs this score can use
- Health: active
- Instruction depth: not yet graded
- License: MIT
- Official: no

## Install

```sh
cp -r formal-methods-guide ~/.claude/skills/
```

## Security audit
Not scanned. We audit npm-published capabilities; this one has no npm package we can resolve, or has not reached the queue. This is not a clean bill of health.

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Measured 2026-08-20 by tashan (https://tashan.sh) from public evidence. Scorer s5.