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yoneda_embedding [2015/03/14 01:10]
nikolaj
yoneda_embedding [2015/03/14 01:13]
nikolaj
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 $h\circ g : \mathrm{Hom}(X,​A)$ ... $f\circ h\circ g : \mathrm{Hom}(X,​B)$ ​ $h\circ g : \mathrm{Hom}(X,​A)$ ... $f\circ h\circ g : \mathrm{Hom}(X,​B)$ ​
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 +Note how the $\mathrm{Hom}$-functors themselves are contravariant,​ as seen by the direction of the vertical arrows: $g: X\to Y$ but e.g. the associated fmap goes from $\mathrm{Hom}(Y,​A)$ to $\mathrm{Hom}(X,​A)$.
  
 === Yoneda lemma === === Yoneda lemma ===
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