lean-ja / lean-ja/lean-by-example
証明無関係ではないと、何が困るのか？
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- Dominant language
- Lean
- Stars
- 188
- Forks
- 15
- Avg merge
- 9h 8m
- Merged PRs (30d)
- 6
Description
たとえば Fin n → Nat という標準的な埋め込み関数を考える。
このとき証明無関係ではない場合、「x < nの証明」が一意ではないため、この関数が単射になるとは限らない。
結果、標準的な埋め込みが単射にならないという気持ち悪い現象が発生してしまう。
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
No file, test, or entry point is named. Start by locating the material that discusses proof irrelevance and the Fin n → Nat embedding, then document a clear explanation of whether non-unique proofs can affect injectivity and what the consequence is.
Written by the indexing model from the issue text.
Assessment
- Domain
- documentation
- Issue type
- Documentation
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Quiet
- Clarity
- Needs clarification
- Newbie friendliness
- 35/100