ThmDex – An index of mathematical definitions, results, and conjectures.

ThmDex – An index of mathematical definitions, results, and conjectures.

Result R463 on D942: Propositional tautology

Law of the excluded middle is a propositional tautology

Formulation 0

Let $\phi \in \text{Proposition}$ be a D2966: Propositional expression.

Then \begin{equation} \models \phi \lor \neg \phi \end{equation}