\begin{tabbing}
$\vdash$  \=$\forall$$T$:Type, $L$:($T$ List), $x$, $y$:$T$.\+
\\[0ex]no\_repeats($T$;$L$)
\\[0ex]$\Rightarrow$ adjacent($T$;$L$;$x$;$y$)
\\[0ex]$\Rightarrow$ ($\forall$$z$:$T$. $z$ before $y$ $\in$ $L$ $\Rightarrow$ ($z$ before $x$ $\in$ $L$ $\vee$ ($z$ = $x$)))
\-
\end{tabbing}