Exercise 20.
Suppose \(P_1, P_2, \ldots, P_n\) and \(Q\) are (possibly molecular) propositional statements. Suppose further that
\(P_1\) | |
\(P_2\) | |
\(\vdots\) | |
\(P_n\) | |
\(\therefore\) | \(Q\) |
is a valid deduction rule. Prove that the statement
\begin{equation*}
(P_1 \wedge P_2 \wedge \cdots \wedge P_n) \imp Q
\end{equation*}
is a tautology.