leanprover-community / leanprover-community/mathlib4
`ring_nf` suggested even when `ring` completes goal
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Description
Example:
import Mathlib
open Real Complex in
lemma test (N : ℕ) (j : ZMod N) :
exp (2 * ↑π * I * ↑j.val / ↑N) = exp (2 * ↑π * (↑j.val / ↑N) * I) := by
ring
Try this: ring_nf
Zulip thread: https://leanprover.zulipchat.com/#narrow/channel/116395-maths/topic/noisy.20ring/with/329038837
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 with the reported ring and ring_nf example in the issue and inspect how the ring tactic emits the “Try this” suggestion after the goal is already closed. Reproduce the behavior in a minimal Mathlib file, then verify that successful ring proofs no longer suggest ring_nf while relevant suggestions still appear when appropriate.
Written by the indexing model from the issue text.
Assessment
- Domain
- tooling
- Issue type
- Bug
- Difficulty
- 3/5
- Estimated time
- 1-2 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100