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@Alizter Alizter commented Mar 12, 2024

We were missing the bifunctor coherence for composition. This lets us prove the exchange law in a (2,1)-category.

is1gpd_hom : forall (a b : A), Is1Gpd (a $-> b) ;
is1functor_postcomp : forall (a b c : A) (g : b $-> c), Is1Functor (cat_postcomp a g) ;
is1functor_precomp : forall (a b c : A) (f : a $-> b), Is1Functor (cat_precomp c f) ;
bifunctor_coh_comp : forall {a b c : A} {f f' : a $-> b} {g' g'' : b $-> c}
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Not sure about this name. We could refactor this after #1886 and ask for composition to be a bifunctor instead.

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@Alizter Alizter Mar 12, 2024

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I'm also not sure about the direction. I've opted for $@L and $@R first but the other direction would be fine too.

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The name seems ok. I might switch the direction, since the one place it is used, it is in the other direction. It's probably most important to be consistent with Bifunctor.v, if that determines it.

@Alizter Alizter requested a review from jdchristensen March 12, 2024 15:00
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I'll look over the rest in a bit.

is1gpd_hom : forall (a b : A), Is1Gpd (a $-> b) ;
is1functor_postcomp : forall (a b c : A) (g : b $-> c), Is1Functor (cat_postcomp a g) ;
is1functor_precomp : forall (a b c : A) (f : a $-> b), Is1Functor (cat_precomp c f) ;
bifunctor_coh_comp : forall {a b c : A} {f f' : a $-> b} {g' g'' : b $-> c}
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The name seems ok. I might switch the direction, since the one place it is used, it is in the other direction. It's probably most important to be consistent with Bifunctor.v, if that determines it.

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The rest LGTM.

@Alizter Alizter force-pushed the ps/rr/add_missing_coherence_for_twoonecat branch from 809accd to 4155e5d Compare March 12, 2024 21:09
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Alizter commented Mar 12, 2024

@jdchristensen I've addressed your comments.

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LGTM (modulo the build failures).

@Alizter Alizter force-pushed the ps/rr/add_missing_coherence_for_twoonecat branch from 4155e5d to a909857 Compare March 13, 2024 12:01
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Alizter commented Mar 13, 2024

Oops, should be fixed now. I had changed the direction of the coherence but not updated the other files.

Alizter added 2 commits March 13, 2024 13:03
We were missing the bifunctor coherence for composition. This lets us
prove the exachange law in a (2,1)-category.

Signed-off-by: Ali Caglayan <[email protected]>

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Signed-off-by: Ali Caglayan <[email protected]>
@Alizter Alizter force-pushed the ps/rr/add_missing_coherence_for_twoonecat branch from a909857 to 07a55d8 Compare March 13, 2024 12:03
@Alizter Alizter merged commit 07d3120 into HoTT:master Mar 14, 2024
@Alizter Alizter deleted the ps/rr/add_missing_coherence_for_twoonecat branch March 14, 2024 15:14
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2 participants