Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Add discrete categories #638

Merged
merged 4 commits into from
Nov 25, 2021
Merged

Add discrete categories #638

merged 4 commits into from
Nov 25, 2021

Conversation

barrettj12
Copy link
Contributor

I've defined discrete categories using Hom[ x , y ] = x ≡ y.

I'm now trying to show that a function f : A → ob C determines a Functor (Discrete A) C, but I'm having trouble showing that this preserves composition. Maybe someone else can help.

@kangxyz
Copy link
Contributor

kangxyz commented Nov 21, 2021

I think you can use J-rule twice, so you only need to treat composition of identity morphisms.

@barrettj12
Copy link
Contributor Author

Makes sense, but I'm not quite sure how to apply J here.

I think the problem might be that given p : x ≡ y and q : y ≡ z

  • F p and F (p ∙ q) are obtained by transport from id {F x}
  • F q is obtained from id {F y}

so it's not clear how to compose them.

@barrettj12 barrettj12 changed the title [help-wanted] Add discrete categories Add discrete categories Nov 21, 2021
@barrettj12 barrettj12 marked this pull request as ready for review November 21, 2021 18:26
Copy link
Collaborator

@mortberg mortberg left a comment

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Just a name change suggestion

Cubical/Categories/Instances/Discrete.agda Outdated Show resolved Hide resolved
@mortberg mortberg merged commit 9173d01 into agda:master Nov 25, 2021
@barrettj12 barrettj12 deleted the discrete branch November 25, 2021 21:51
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Labels
None yet
Projects
None yet
Development

Successfully merging this pull request may close these issues.

3 participants