Timeline for "Philosophical" meaning of the Yoneda Lemma
Current License: CC BY-SA 3.0
8 events
| when toggle format | what | by | license | comment | |
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| Oct 5, 2015 at 20:05 | history | made wiki | Post Made Community Wiki by Todd Trimble | ||
| Feb 25, 2013 at 13:07 | history | edited | Tom Leinster | CC BY-SA 3.0 |
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| Apr 19, 2012 at 13:45 | comment | added | Tom Leinster | Not off the top of my head. The only thing I can think of is that Joyal's theory of species is a categorical approach to enumerative combinatorics, and is almost certain to involve the Yoneda lemma in its development. | |
| Apr 19, 2012 at 7:16 | comment | added | Yannic | @Tom: Do you know some applications of Yoneda lemma to combinatorics? | |
| Nov 18, 2009 at 1:26 | comment | added | Tom Leinster | Max M, sorry, I only just saw your question. Urs is right: I was referring to the fact that every presheaf is a colimit, in a canonical way, of representable presheaves. I'd call it that the 'Density formula'. Another reference is Theorem 5.1.16 of these notes: maths.gla.ac.uk/~tl/msci . Don't take the analogy with prime factorization too seriously. | |
| Nov 17, 2009 at 17:04 | comment | added | Urs Schreiber | This refers to the "co-Yoneda lemma", which says that every presheaf is a colimit of representable presheaves: ncatlab.org/nlab/show/co-Yoneda+lemma | |
| Nov 2, 2009 at 1:34 | comment | added | Max M | Could you explain the last statement on page 8? (Any functor C^op \mapsto Set can be built out of representables Hom(-,A) in very roughly the same way that any number is built as a product of primes). Should I make it a separate question? | |
| Oct 29, 2009 at 4:03 | history | answered | Tom Leinster | CC BY-SA 2.5 |