deletions | additions       diff --git a/Ex 1.tex b/Ex 1.tex  index 3c36214..d9ed513 100644  --- a/Ex 1.tex  +++ b/Ex 1.tex 
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\land & (x \leq 0 \to (0 \leq x \a (0 \leq x \to x = x) \a (x < 0 \to x = -x)))\\  \iff & (x < 0 \to -x = -x) \a (0 \leq x \to x = x)\\  \iff & \T\\  \end{split}  \end{equation}  Therefore:  \begin{equation}  \begin{split}  Q \implies& \T  \end{split}  \end{equation} In other words, the post condition holds for all possible pre conditions.