$\forall$$A$:MsgA, $x$:Id, $k$:Knd.
\\[0ex]Feasible($A$) $\Rightarrow$ ($<$$k$, $x$$>$ $\in$ dom(($A$.2.2.2.2).1) = tt $\in$ $\mathbb{B}$) $\Rightarrow$ $A$.aframe($k$ affects $x$)