$\forall$$A$:MsgA, $x$:Id, $k$:Knd.
\\[0ex]Feasible($A$)
\\[0ex]$\Rightarrow$ $\langle$$k$$,\,$$x$$\rangle$ $\in$ dom(1of(2of(2of(2of(2of($A$)))))) $=$ true$_{2}$ $\in$ $\mathbb{B}$
\\[0ex]$\Rightarrow$ $A$.aframe($k$ affects $x$)