leanprover-community / leanprover-community/mathlib4
Tracking: explicit universes can improve performance substantially
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performance-hack
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Description
For AlgebraicGeometry.Scheme and similar bundled categories, elaboration seems to inject level metavariables resulting more steps in unification. Providing explicit universe annotations, Scheme.{u}, prevents this.
It would nice to understand what is happening.
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 or test is named. Start by reproducing the elaboration behavior for AlgebraicGeometry.Scheme and similar bundled categories, comparing implicit levels with explicit Scheme.{u} annotations. Done means explaining the source of the extra unification work and identifying a concrete, validated way to improve it.
Written by the indexing model from the issue text.
Assessment
- Domain
- compilers
- Issue type
- Bug
- Difficulty
- 5/5
- Estimated time
- Over a week
- Activity status
- Stale
- Clarity
- Needs clarification
- Newbie friendliness
- 25/100