leanprover-community / leanprover-community/mathlib4
Notation for multilinear maps
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Description
In #42534 MultilinearMap gets semilinearized and writing a multilinear map is now a bit awkward, because one needs to specify RingHom.id R, not R. The solution to this is that MultilinearMap should have notation, similar to ContinuousMultilinearMap:
@[inherit_doc ContinuousMultilinearMap]
notation3:25 M " [×" n "]→L[" R "] " M' => ContinuousMultilinearMap R (fun _i : Fin n => M) M'
with a variant for semilinear.
cc: @gloges
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 semilinearization in #42534 and the existing ContinuousMultilinearMap notation. Add analogous notation for MultilinearMap, including the semilinear variant, and confirm that multilinear maps can be written without explicitly specifying RingHom.id R.
Written by the indexing model from the issue text.
Assessment
- Domain
- tooling
- Issue type
- Feature
- Difficulty
- 2/5
- Estimated time
- 1-3 hours
- Activity status
- Active
- Clarity
- Mostly clear
- Newbie friendliness
- 72/100