Biconditional is Commutative/Formulation 1/Proof by Truth Table
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Theorems
- $p \iff q \dashv \vdash q \iff p$
Proof
We apply the Method of Truth Tables.
As can be seen by inspection, the truth values under the main connectives match for all boolean interpretations.
$\begin{array}{|ccc||ccc|} \hline
p & \iff & q & q & \iff & p \\
\hline
\F & \T & \F & \F & \T & \F \\
\F & \F & \T & \T & \F & \F \\
\T & \F & \F & \F & \F & \T \\
\T & \T & \T & \T & \T & \T \\
\hline
\end{array}$
$\blacksquare$