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Add algebra morphism identity and composition constructions #1502

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Merged
merged 6 commits into from
Jun 20, 2021

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Taneb
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@Taneb Taneb commented May 14, 2021

Closes #1500

I made slight changes to the IsLattice and Lattice records.

Parts of this PR worry me that the definition of RingHomomorphism etc is incorrect, as they carry two proofs that the function is congruent modulo the equivalence relation, and as such don't provide any directly

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Thanks for the PR! Looks like quite a tedious one so cheers for doing it.

I've added a few comments that should help reduce some the code needed.

@@ -250,6 +250,42 @@ record IsLattice (∨ ∧ : Op₂ A) : Set (a ⊔ ℓ) where
∨-congʳ : RightCongruent ∨
∨-congʳ y≈z = ∨-cong y≈z refl

∨-isMagma : IsMagma ∨
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Hmm these already exist in Algebra.Properties.Lattice. Not saying that's the right place for them, but using them from there minimises the changes need in this particular PR.

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@Taneb apologies I somehow missed your comment. I've now answered that. Just to say that if you would like to get this included in the upcoming v1.7 release, it'd be great to get this wrapped up relatively soon so I can include it in the release candidate 👍

@MatthewDaggitt MatthewDaggitt removed this from the v1.7 milestone May 27, 2021
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Parts of this PR worry me that the definition of RingHomomorphism etc is incorrect, as they carry two proofs that the function is congruent modulo the equivalence relation, and as such don't provide any directly

Yes, the situation is not very pleasing, I agree. If you have any practical suggestions to fix it, please do open an issue or a PR?

@MatthewDaggitt MatthewDaggitt added this to the v1.8 milestone Jun 13, 2021
@MatthewDaggitt MatthewDaggitt merged commit d8d9248 into agda:master Jun 20, 2021
@MatthewDaggitt MatthewDaggitt modified the milestones: v1.8, v2.0 Jul 6, 2021
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Proofs that identity and composition of homomorphisms are homomorphisms
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