nLab
cospan

Definition

In any category, a cospan is a diagram like this:

$$\array{ && a &&&& b \\ & && {}_{f}\searrow & & \swarrow_g && \\ &&&& c &&&& }$$

A cospan that admits a cone is called a quadrable cospan.

A cospan in the category $C$ is the same as a span in the opposite category $C^{op}$. So, all general facts about cospans in $C$ are general facts about spans in $C^{op}$, and the reader may turn to the entry on spans to learn more.

See also

• Cospans in Algebraic Topology
• multispan
• the cograph of a function
• the cograph of a functor