# adjunction

*Noun.*The act of joining; the thing joined or added.*Noun.*(*category theory*) A form of similarity between a pair of categories $mathcal\{C\}$ and $mathcal\{D\}$ which is weaker than equivalence, which in turn is weaker than isomorphism. Given functors $F:mathcal\{C\}\; ightarrow\; mathcal\{D\}$ and $G:mathcal\{D\}\; ightarrow\; mathcal\{C\}$, ''F'' is "left adjoint" of ''G'', and ''G'' "right adjoint" of ''F'', denoted as $F\; dashv\; G$, if .

This is an unmodified, but possibly outdated, definition from Wiktionary and used here under the Creative Commons license. Wiktionary is a great resource. If you like it too, please donate to Wikimedia.

This entry was last updated on RefTopia from its source on 3/20/2012.