Definition:Cone (Category Theory)

Definition
Let $\mathbf C$ be a metacategory.

Let $D: \mathbf J \to \mathbf C$ be a $\mathbf J$-diagram in $\mathbf C$.

A cone to $D$ comprises an object $C$ of $\mathbf C$, and a morphism:


 * $c_j: C \to D_j$

for each object of $\mathbf J$, such that for each morphism $\alpha: i \to j$ of $\mathbf J$:


 * $\begin{xy}\xymatrix@+0.5em@L+2px{

C \ar[d]_*+{c_i} \ar[dr]^*+{c_j}

\\ D_i \ar[r]_*+{D_\alpha} & D_j }\end{xy}$

is a commutative diagram.

Also see

 * Definition:Cocone, the dual notion.