Definition:Two (Category)

This page is about Two in the context of Category Theory. For other uses, see Two.

Definition

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

$\quad * \longrightarrow \star$

with:

Two objects, $*$ and $\star$

Three morphisms:

The identity morphism $I_*$

The identity morphism $I_\star$

One non-identity morphism $* \to \star$

Also see

• Definition:Empty Category
• Definition:One (Category)
• Definition:Three (Category)

Sources

• 2010: Steve Awodey: Category Theory (2nd ed.) ... (previous) ... (next): $\S 1.4.5$