Let \(C\) be a category that has finite limits and let \(x:C\) be an object. Let \({x}^{*}:C\rightarrow C/x\) denote the pullback functor along the morphism from \(x\) to the final object. We define a morphism in \(C/x\)

\(\mathord {\textnormal {\textsf {d}}}_{x}:\mathord {\textnormal {\textsf {1}}}\rightarrow {x}^{*}(x)\) to be the one represented by the diagonal morphism \(x\rightarrow x\times x\) in \(C\).