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3.4 Logical Equivalence

Sometimes two distinct sentences have exactly the same truth values in all circumstances. Such sentences are logically equivalent.

  1. $ p\rightarrow q$
  2. $ \neg p \vee q$
  3. $ \neg q \rightarrow \neg p$
  4. \begin{displaymath}
\begin{array}[t]{\vert c\vert c\vert c\vert\vert c\vert c\ve...
...{\:T\:} & \mathrm{\:T\:} & \mathrm{\:T\:}\\
  5. $ (\neg p \vee q) \Longleftrightarrow (p \rightarrow q)
(\neg q \rightarrow \neg p)$

Jean Mark Gawron 2009-02-16