Opposite category

Let $𝖢$ be a category. The opposite category $𝖢 𝐨 𝐩$ is the category with the same objects as $𝖢$ but whose morphisms have the domain and codomain swapped, #m/def/cat i.e.

𝑓 \in 𝖢 (𝑋, 𝑌) ⟺ 𝑓 \in 𝖢 𝐨 𝐩 (𝑌, 𝑋)

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