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

    being equipped with equalities

    \[ \begin{gathered} R^{\otimes }_{-1|U,V} \colon R_{-1}\webleft (U\cap V\webright ) \mathbin {\overset {=}{\rightarrow }}R_{-1}\webleft (U\webright )\cap R_{-1}\webleft (V\webright ),\\ R^{\otimes }_{-1|\mathbb {1}} \colon R_{-1}\webleft (A\webright ) \mathbin {\overset {=}{\rightarrow }}B, \end{gathered} \]

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


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