From 8aac808eace33d4cd0ae2903f310fb2266f36dc8 Mon Sep 17 00:00:00 2001 From: Patrick Stevens <3138005+Smaug123@users.noreply.github.com> Date: Sun, 12 May 2024 10:25:47 +0100 Subject: [PATCH] Fix a typo (#12) --- hugo/content/posts/2024-04-13-yoneda.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/hugo/content/posts/2024-04-13-yoneda.md b/hugo/content/posts/2024-04-13-yoneda.md index e27678a..65789d5 100644 --- a/hugo/content/posts/2024-04-13-yoneda.md +++ b/hugo/content/posts/2024-04-13-yoneda.md @@ -79,7 +79,7 @@ This somehow "captures exactly all the structure that \\(\mathcal{C}\\) said \\( (I've used the symbol \\(\mathrm{Rep}\\) to denote these diagrams, because the category-theoretic term for a diagram isomorphic to one of these is "*representable functor*".) Note that I haven't yet written down the functions in these concrete instantiations of \\(\mathcal{C}\\); there's only one thing it could plausibly be. -Given \\(f : B \to C\\) a morphism of \\(\mathcal{C}\\), the corresponding function \\(\mathrm{Rep}_A(f) : \mathrm{Rep}_A(B) \to \mathrm{Rep}_A(C)\\) (that is, the function \\(\mathrm{Rep}_A(f) : \langle \text{morphisms $A \to B$ in $\mathcal{C}$} \rangle \to \langle\text{morphisms $A \to C$ in $\mathcal{C}$}\rangle\\) is defined to be given by composing with \\(f\\): we send \\(g : A \to B\\) to \\(f \circ g : A \to C\\). +Given \\(f : B \to C\\) a morphism of \\(\mathcal{C}\\), the corresponding function \\(\mathrm{Rep}_A(f) : \mathrm{Rep}_A(B) \to \mathrm{Rep}_A(C)\\) (that is, the function \\(\mathrm{Rep}_A(f) : \langle \text{morphisms $A \to B$ in $\mathcal{C}$} \rangle \to \langle\text{morphisms $A \to C$ in $\mathcal{C}$}\rangle\\)) is defined to be given by composing with \\(f\\): we send \\(g : A \to B\\) to \\(f \circ g : A \to C\\). These particular diagrams, the *representable functors* (one for every object in \\(\mathcal{C}\\)), together tell you everything there is to know about the category. (That is kind of intuitive, by their definition as "the sets of morphisms": we can list out every morphism in the category, just by writing down every element of every object in each of these concrete instantiations.)