• Symmetric Strict Monoidality With Respect to Intersections. The inverse image function of Item 1 has a symmetric strict monoidal structure
    \[ \webleft (f^{-1},f^{-1,\otimes },f^{-1,\otimes }_{\mathbb {1}}\webright ) \colon \webleft (\mathcal{P}\webleft (Y\webright ),\cap ,Y\webright ) \to \webleft (\mathcal{P}\webleft (X\webright ),\cap ,X\webright ), \]

    being equipped with equalities

    \[ \begin{gathered} f^{-1,\otimes }_{U,V} \colon f^{-1}\webleft (U\webright )\cap f^{-1}\webleft (V\webright ) \mathbin {\overset {=}{\rightarrow }}f^{-1}\webleft (U\cap V\webright ),\\ f^{-1,\otimes }_{\mathbb {1}} \colon X \mathbin {\overset {=}{\rightarrow }}f^{-1}\webleft (Y\webright ), \end{gathered} \]

    natural in $U,V\in \mathcal{P}\webleft (Y\webright )$.


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