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$\forall$\=${\it es}$:event\_system\{i:l\}, $e_{1}$:es{-}E(${\it es}$), $e_{2}$:\{$e$:es{-}E(${\it es}$)$\mid$ loc($e$) = loc($e_{1}$) $\in$ Id\} ,\+
\\[0ex]$p$:(\{$e$:es{-}E(${\it es}$)$\mid$ loc($e$) = loc($e_{1}$) $\in$ Id\} $\rightarrow$prop\{i:l\}). $e_{2}$ = first $e$ $\geq$ $e_{1}$.$p$($e$) $\in$ prop\{i:l\}
\-
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