Basic Examples of Propositional Calculus

tautology

equivalence

valid argument

invalid argument

new statement/argument

1

p	p∨¬p
True	True
False	True

This Demonstration uses truth tables to verify some examples of propositional calculus.

A sentence is a tautology if and only if every row of the truth table for it evaluates to true. Two sentences are logically equivalent if they have the same truth value in each row of their truth table. An argument is valid if each assignment of truth value that makes all premises true also makes the conclusion true.