Logical OR

Type classification: this is a lesson resource.

Welcome! This is a lesson in the Introductory Discrete Mathematics for Computer Science course here at Wikiversity.

Previous lesson: Logical AND

The Disjunction

I apologize for the name of this lesson. The true name of this operator, which is a diadic operator, is a disjunction. It is sometimes called the inclusive OR operator, to distinguish it from another operator you'll learn about later. However, it is a bit dangerous to refer to a disjunction as an OR operator, because English words are far more vague than logic.

$\vee$ : This is the disjunction, a.k.a. the (inclusive) OR operator

Let $p$ represent the statement: It is raining.

Let $q$ represent the statement: I am hungry.

$p\vee q$ represents the disjunction of statements $p$ and $q$: It is raining OR I am hungry (OR it is raining AND I am hungry).

Truth Table for the Disjunction

This is its truth table:

$p\,\!$	$q\,\!$	$p\vee q$
T	T	T
T	F	T
F	T	T
F	F	F

Next Lesson

The name of the next lesson is Logical XOR.