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feat(combinatorics/quiver): isomorphisms of quivers #18511
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Yeah I think that's common practice. |
Thanks, I'm sometimes reluctant to do it in instances (like this one) where I asked for help and got a ready-to-use piece of code: the co-authored-by line could signal explicit co-authorship, when I just took the code and the other person didn't have a say in the result. I'm not sure that makes sense? |
I think the main point of the "co-authored-by" lines is that they go into the commit message and are collected into stats like the Authors table here. |
Co-authored-by: Yaël Dillies <[email protected]>
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Can you show that an equivalence of categories is an isomorphism of quivers?
No, since an equivalence is just "essentially surjective on objects" while an isomorphism of quivers is bijective on objects (afaiu). |
But on that subject, I don't know to what extent I should try and build conversions between all this quiver stuff and categories. |
The simple fact that it can be done is enough motivation I think. This might display gaps in the API. |
But that would be work for another PR in any case, no? |
Well, no, I want to see whether there are gaps in your API now. |
I don't follow; what type of gaps would you like to see? Could you give me some signatures or more concrete infos? |
@@ -61,7 +61,7 @@ lemma ext {V : Type u} [quiver.{v₁} V] {W : Type u₂} [quiver.{v₂} W] | |||
{F G : prefunctor V W} | |||
(h_obj : ∀ X, F.obj X = G.obj X) | |||
(h_map : ∀ (X Y : V) (f : X ⟶ Y), | |||
F.map f = eq.rec_on (h_obj Y).symm (eq.rec_on (h_obj X).symm (G.map f))) : F = G := | |||
F.map f = eq.rec_on (h_obj X).symm (eq.rec_on (h_obj Y).symm (G.map f))) : F = G := |
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Why swap X
and Y
here?
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Can't say for sure, it's been a long time.
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Could you investigate and either revert or add a comment?
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I'm kind of out of the loop on all this, but after trying it out in gitpod, it seems swapping X
and Y
works for the ext
lemma itself, but then of_bijective
and further lemmas in the iso
file get failing proofs, which I couldn't debug.
A comment as to that is what I should do?
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( ping @semorrison )
bors d+ |
✌️ bottine can now approve this pull request. To approve and merge a pull request, simply reply with |
Co-authored-by: Adam Topaz [email protected]
The
of_bijective
part has been kindly provided by @adamtopaz, can I add aco-authored-by
line?