problems/0004.md

Theorem: Let $\{*\}\in\mathcal{S}\mathrm{et}$ be the terminal object in $\mathcal{S}\mathrm{et}$.Then $\hom_{\mathcal{S}\mathrm{et}}(\{*\},-):\mathcal{S}\mathrm{et}\to\mathcal{S}\mathrm{et}$ is an equivalence of categories.