leanprover-community / leanprover-community/mathlib4
Diamond for `CompleteBooleanAlgebra` of `Set`'s
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Description
From leanprover/mathlib#16932, we have
import Mathlib.Data.Set.Lattice
variable {α : Type*}
-- Succeeds
example : @Set.instBooleanAlgebraSet α = Pi.booleanAlgebra := by
with_reducible_and_instances rfl
-- Fails
example : (@Set.completeAtomicBooleanAlgebra α).toCompleteBooleanAlgebra = Pi.completeBooleanAlgebra := rfl
See also the Zulip discussion
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 reproducer in the issue, importing Mathlib.Data.Set.Lattice and comparing the two instance equalities. Read the linked Zulip discussion for the context around the CompleteBooleanAlgebra instances. Done means the second equality involving Set.completeAtomicBooleanAlgebra and Pi.completeBooleanAlgebra no longer fails.
Written by the indexing model from the issue text.
Assessment
- Domain
- tooling
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Quiet
- Clarity
- Mostly clear
- Newbie friendliness
- 48/100