Rule of Distribution/Disjunction Distributes over Conjunction/Left Distributive/Formulation 1/Proof by Truth Table
Theorem
- $p \lor \paren {q \land r} \dashv \vdash \paren {p \lor q} \land \paren {p \lor r}$
Proof
We apply the Method of Truth Tables to the proposition.
As can be seen by inspection, the truth values under the main connectives match for all boolean interpretations.
$\begin{array}{|ccccc||ccccccc|} \hline p & \lor & (q & \land & r) & (p & \lor & q) & \land & (p & \lor & r) \\ \hline \F & \F & \F & \F & \F & \F & \F & \F & \F & \F & \F & \F \\ \F & \F & \F & \F & \T & \F & \F & \F & \F & \F & \T & \T \\ \F & \F & \T & \F & \F & \F & \T & \T & \F & \F & \F & \F \\ \F & \T & \T & \T & \T & \F & \T & \T & \T & \F & \T & \T \\ \T & \T & \F & \F & \F & \T & \T & \F & \T & \T & \T & \F \\ \T & \T & \F & \F & \T & \T & \T & \F & \T & \T & \T & \T \\ \T & \T & \T & \F & \F & \T & \T & \T & \T & \T & \T & \F \\ \T & \T & \T & \T & \T & \T & \T & \T & \T & \T & \T & \T \\ \hline \end{array}$
$\blacksquare$