leanprover-community / leanprover-community/mathlib4

chore(FieldTheory/Finite): switch from Fintype to Finite/Nat.card

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Description

like what @tb65536 has done for finite group theory in #6081, #13431, #13432, #13630, #13637, #14789, #14854, #14856, #19074.

The files in question:
https://github.com/leanprover-community/mathlib4/blob/f2bf11f4287d61b6fe50ea974ac1a849060e955e/Mathlib/FieldTheory/Finite/Basic.lean
https://github.com/leanprover-community/mathlib4/blob/f2bf11f4287d61b6fe50ea974ac1a849060e955e/Mathlib/FieldTheory/Finite/GaloisField.lean
possibly also MvPolynomial.R etc.

Requires Nat.card version of theorems like Module.card_eq_pow_finrank: here we only need to assume [Finite V], not [Finite K]. (Update: this particular lemma has been added in #24407.)

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First steps

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  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by comparing the finite-group changes in issues #6081, #13431, #13432, #13630, #13637, #14789, #14854, #14856, and #19074. Read Mathlib/FieldTheory/Finite/Basic.lean and GaloisField.lean, then inspect MvPolynomial.R and the Nat.card form of Module.card_eq_pow_finrank. Done means the FieldTheory/Finite results use Finite/Nat.card consistently, including the required theorem assumptions.

Written by the indexing model from the issue text.

Assessment

Domain
devtools
Issue type
Refactor
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
38/100

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