Notes by Lex

A declarative sentence that is either true or false, but not both, is a proposition.

Also known as a statement.

Usually denoted using lowercase letters $p$, $q$, $r$, $s$ or $t$.

These sentences would be considered propositions:

• It is Monday today.
• I am 14 years old.
• 1 + 1 = 3

The truthfulnes or falsity of a proposition is called its Truth Value. Denoted by $T$ or $F$, or 1 and 0 in computer science.