Definition:Two (Category)

Definition
The category $\mathbf 2$, two, is the category:


 * $\qquad * \longrightarrow \star$

with:


 * Two objects, $*$ and $\star$; and
 * Three morphisms:


 * The identity morphism $\operatorname{id}_*$;
 * The identity morphism $\operatorname{id}_\star$;
 * One non-identity morphism $* \to \star$.

Also see

 * Definition:Empty Category
 * Definition:Trivial Category
 * Definition:Three (Category)