leanprover-community / leanprover-community/mathlib4
Lightweight variant of `group`
Nobody has claimed this yet.
- Dominant language
- Lean
- Stars
- 4.2k
- Forks
- 1.7k
- PR merge metrics
- No merged PRs in 30d
Description
group is a very heavy tactic (it imports ring to normalise exponents) which is no more powerful than simp [mul_assoc] in many cases appearing in practice. It might be useful to have a lightweight variant of group (in the sense that it doesn't import Field or even MonoidWithZero) for those numerous cases.
List of PRs removing uses of group:
- #21296
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
Start by reading the group tactic and the import concerns described in the issue, especially the roles of ring, Field, and MonoidWithZero. Review PR #21296 and the linked Zulip discussion to understand existing removals and the intended lightweight scope; done means a suitable variant is defined and the relevant heavy imports are no longer required for those cases.
Written by the indexing model from the issue text.
Assessment
- Domain
- tooling
- Issue type
- Feature
- Difficulty
- 5/5
- Estimated time
- Over a week
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100