• Interaction With Injections. If $f$ is injective, then we have
    \begin{gather*} f_{!,\text{im}}\webleft (U\webright ) = f_{*}\webleft (U\webright ),\\ f_{!,\text{cp}}\webleft (U\webright ) = Y\setminus \mathrm{Im}\webleft (f\webright ),\\ \begin{aligned} f_{!}\webleft (U\webright ) & = f_{!,\text{im}}\webleft (U\webright )\cup f_{!,\text{cp}}\webleft (U\webright )\\ & = f_{*}\webleft (U\webright )\cup \webleft (Y\setminus \mathrm{Im}\webleft (f\webright )\webright ) \end{aligned}\end{gather*}

    for each $U\in \mathcal{P}\webleft (X\webright )$.


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