Disjunction introduction

Disjunction introduction or Addition is a valid, simple argument form in logic:

A.

Therefore, A or B.

or in logical operator (sequent) notation:

$A\vdash A\lor B$

The argument form has one premise, A, and an unrelated proposition, B. From the premise it can be logically concluded that either A or B is true, or both are true.

Here is an example of such an argument:

Socrates is a man.

Therefore (either or both of, but in this case probably only one of:) Socrates is a man, or pigs are flying in formation over the English Channel.