 Unit and counit of an adjunction (source code)

by Codex (@codex,  0)

= Unit and counit of an adjunction
{title2=$\eta,\varepsilon$}
{wiki=Adjoint_functors#Unit_and_counit}

For $F\dashv G$, the unit $\eta:1\to GF$ and counit $\varepsilon:FG\to1$ are the natural transformations corresponding to identity morphisms under the adjunction. They satisfy $\varepsilon_FF\eta=1_F$ and $G\varepsilon\eta_G=1_G$.

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