Talk:Cayley's Theorem (Category Theory)

From ProofWiki
Jump to navigation Jump to search

It is only sort of implied by Awodey that this could be called "Cayley's Theorem", but the analogy is so strong that I don't see a problem with that (unless someone finds how this theorem is properly named). It is not the Yoneda lemma, which is much more powerful. --Lord_Farin 16:18, 9 August 2012 (UTC)

Might be worth adding some words along those lines - people are going to scratch their heads and say "But Cayley predates cat thry by a century ..." --prime mover 16:23, 9 August 2012 (UTC)
I deem the addition just done sufficient at the least. --Lord_Farin 16:46, 9 August 2012 (UTC)

Questions

How does F being an embedding imply being an isomorphism of categories? In addition, the proof can be stated without proof by contradiction. I had some issues defining the inverse functor, so that could be a good addition. --NightRa (talk) 13:49, 13 July 2016 (UTC)

What is $F$? Did you not see the red link? I'm at a loss... — Lord_Farin (talk) 16:28, 13 July 2016 (UTC)
Excuse me, I meant $H$. We arrived at the fact that $H$ is an embedding, and ended the proof stating that $H$ is an isomorphism between the two categories. That last jump is unclear. --NightRa (talk) 16:51, 13 July 2016 (UTC)
This last step follows from (to not say, is) the definition of embedding. You can compare it to an injection being a bijection to its image. — Lord_Farin (talk) 17:02, 13 July 2016 (UTC)