Solution set

Set

 context $X$ context $\langle Y,y_0 \rangle$ … pointed set context $f:X\to Y$ definition $S := \{x\mid f(x)=y_0\}$

$S=f^{-1}(\{y_0\})$ where $f^{-1}:{\mathcal P}Y\to{\mathcal P}X$.

Reference

Wikipedia: Solution set