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$\forall$$w$:World.
\\[0ex]FairFifo
\\[0ex]$\Rightarrow$ \=($\forall$$e$:E. d($e$;$e$) $=$ 0)\+
\\[0ex]\& ($\forall$$e$, ${\it e'}$:E. d($e$;${\it e'}$) $=$ d(${\it e'}$;$e$) $\in$ $\mathbb{Z}$)
\\[0ex]\& ($\forall$$e$, ${\it e'}$, ${\it e''}$:E. $e$ $<$c ${\it e'}$ $\Rightarrow$ ${\it e'}$ $<$c ${\it e''}$ $\Rightarrow$ d($e$;${\it e''}$) $=$ d($e$;${\it e'}$)+d(${\it e'}$;${\it e''}$))
\-
\end{tabbing}