$\forall$${\it the\_es}$:event\_system\{i:l\}, ${\it e'}$,$e$:es{-}E(${\it the\_es}$). ($e$ $\in$ before(${\it e'}$)) $\Leftarrow\!\Rightarrow$ es{-}locl(${\it the\_es}$; $e$; ${\it e'}$)