Tautology

A formula that is always true for the inputs given. Example: $P\vee \neg P$ will be true for all statements $P$ Opposed to a Contradiction

Tautology Laws

• $P\wedge$ (a tautology) $\equiv P$
• $P\vee$ (a tautology) $\equiv$ $T$
• $\neg$ (a tautology) $\equiv$ a Contradiction