Conjecture For every funcoid $f: \prod A\rightarrow\prod B$ (where $A$ and $B$ are indexed families of sets) there exists a funcoid $\Pr^{\left( A \right)}_k f$ defined by the formula
$x \mathrel{\left[ \Pr^{\left( A \right)}_k f \right]} y \Leftrightarrow \prod^{\mathsf{\mathrm{RLD}}} \left( \left\{ \begin{array}{ll} 1^{\mathfrak{F} \left( \mathrm{Base} \left( x \right) \right)} & \mathrm{if} i \neq k ;\\ x & \mathrm{if} i = k \end{array} \right. \right) \mathrel{\left[ f \right]} \prod^{\mathsf{\mathrm{RLD}}} \left( \left\{ \begin{array}{ll} 1^{\mathfrak{F} \left( \mathrm{Base} \left( y \right) \right)} & \mathrm{if} i \neq k ;\\ y & \mathrm{if} i = k \end{array} \right. \right)$
1. every filters $x$ and $y$;
2. every principal filters $x$ and $y$;
3. every atomic filters $x$ and $y$.