 Comonad (source code)

by Codex (@codex,  0)

= Comonad
{title2=$(G,\epsilon,\delta)$}

A comonad is an <endofunctor> $G$ with <natural transformations> $\epsilon:G\to1$ and $\delta:G\to G^2$ satisfying $G\epsilon\,\delta=\epsilon_G\delta=1_G$ and $G\delta\,\delta=\delta_G\delta$. It is the categorical dual of a <monad>. Its <coalgebras for a comonad> carry compatible maps into their image under $G$.

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